Hi Fabrizio, thanks for your patch! On Wed, Oct 31, 2018 at 1:58 PM Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx> wrote: > While adding SiI9022A support to the iwg23s board it came up > that when the HDMI transmitter is in pass through mode the > device is not compliant with the I2C specification anymore, > as it requires a far bigger tbuf due to a delay the HDMI > transmitter is adding when relaying the STOP condition on the > monitor i2c side of things. When not providing an appropriate > delay after the STOP condition the i2c bus would get stuck. > Also, any other traffic on the bus while talking to the monitor > may cause the transaction to fail or even cause issues with the > i2c bus as well. > > I2c-gates seemed to reach consent as a possible way to address > these issues, and as such this patch is implementing a solution > based on that. Since others are clearly relying on the current > implementation of the driver, this patch won't require any DT > changes. > > Since we don't want any interference during the DDC Bus > Request/Grant procedure and while talking to the monitor, we have > to use the adapter locking primitives rather than the i2c-mux > locking primitives, but in order to achieve that I had to get > rid of regmap. Why did you have to remove regmap? It is perfectly possible to override any reading/writing operations locally if you don't want to use the regmap i2c variants. The code in your patch does not make it evident to me exactly where the problem is with regmap, also I bet the regmap maintainer would love to hear about it so we can attempt to fix it there instead of locally in this driver. AFAICT there is some locked vs unlocked business and I strongly hope there is some way to simply pass that down into whatever functions regmap end up calling so we don't have to change all call sites. (So please include Mark Brown on CC in future iterations.) > Signed-off-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx> > --- > Dear All, > > this is a follow up to: > https://www.mail-archive.com/linux-renesas-soc@xxxxxxxxxxxxxxx/msg32072.html > > Comments very welcome! At the very least I think the patch needs to be split in two, one dealing with the locking business and one dealing with the buffer size. As it looks now it is very hard to review. > > Thanks, > Fab > > drivers/gpu/drm/bridge/sii902x.c | 404 ++++++++++++++++++++++++++------------- > 1 file changed, 274 insertions(+), 130 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/sii902x.c b/drivers/gpu/drm/bridge/sii902x.c > index e59a135..137a05a 100644 > --- a/drivers/gpu/drm/bridge/sii902x.c > +++ b/drivers/gpu/drm/bridge/sii902x.c > @@ -21,9 +21,9 @@ > */ > > #include <linux/gpio/consumer.h> > +#include <linux/i2c-mux.h> > #include <linux/i2c.h> > #include <linux/module.h> > -#include <linux/regmap.h> > > #include <drm/drmP.h> > #include <drm/drm_atomic_helper.h> > @@ -82,12 +82,130 @@ > > struct sii902x { > struct i2c_client *i2c; > - struct regmap *regmap; > struct drm_bridge bridge; > struct drm_connector connector; > struct gpio_desc *reset_gpio; > + struct i2c_mux_core *i2cmux; > }; > > +static int sii902x_transfer_read(struct i2c_client *i2c, u8 reg, u8 *val, > + u16 len, bool locked) > +{ > + struct i2c_msg xfer[] = { > + { > + .addr = i2c->addr, > + .flags = 0, > + .len = 1, > + .buf = ®, > + }, { > + .addr = i2c->addr, > + .flags = I2C_M_RD, > + .len = len, > + .buf = val, > + } > + }; > + unsigned char xfers = ARRAY_SIZE(xfer); > + int ret, retries = 5; > + > + do { > + if (locked) > + ret = i2c_transfer(i2c->adapter, xfer, xfers); > + else > + ret = __i2c_transfer(i2c->adapter, xfer, xfers); > + if (ret < 0) > + return ret; > + } while (ret != xfers && --retries); > + return ret == xfers ? 0 : -1; > +} > + > +static int sii902x_bulk_read(struct i2c_client *i2c, u8 reg, u8 *val, u16 len) > +{ > + return sii902x_transfer_read(i2c, reg, val, len, true); > +} > + > +static int __sii902x_bulk_read(struct i2c_client *i2c, u8 reg, u8 *val, u16 len) > +{ > + return sii902x_transfer_read(i2c, reg, val, len, false); > +} I'm not a fan of __functions because it is syntactically ambigous what that means. Example set_bit() vs __set_bit() - is it obvious from context that the latter is non-atomic? No. Give these functions names that indicate exactly what they do and why, please. *_locked and *_unlocked variants? > +static int sii902x_read(struct i2c_client *i2c, u8 reg, u8 *val) > +{ > + return sii902x_bulk_read(i2c, reg, val, 1); > +} > + > +static int __sii902x_read(struct i2c_client *i2c, u8 reg, u8 *val) > +{ > + return __sii902x_bulk_read(i2c, reg, val, 1); > +} Dito > +static int sii902x_transfer_write(struct i2c_client *i2c, u8 *val, > + u16 len, bool locked) > +{ > + struct i2c_msg xfer = { > + .addr = i2c->addr, > + .flags = 0, > + .len = len, > + .buf = val, > + }; > + int ret, retries = 5; > + > + do { > + if (locked) > + ret = i2c_transfer(i2c->adapter, &xfer, 1); > + else > + ret = __i2c_transfer(i2c->adapter, &xfer, 1); This locked variable seems to be the magic dust so please document it thorughly. > + if (ret < 0) > + return ret; > + } while (!ret && --retries); > + return !ret ? -1 : 0; > +} > + > +static int sii902x_bulk_write(struct i2c_client *i2c, u8 *val, u16 len) > +{ > + return sii902x_transfer_write(i2c, val, len, true); > +} > + > +static int sii902x_write(struct i2c_client *i2c, u8 reg, u8 val) > +{ > + u8 data[2] = {reg, val}; > + > + return sii902x_transfer_write(i2c, data, 2, true); > +} > + > +static int __sii902x_write(struct i2c_client *i2c, u8 reg, u8 val) > +{ > + u8 data[2] = {reg, val}; > + > + return sii902x_transfer_write(i2c, data, 2, false); > +} > + > +static int sii902x_update_bits(struct i2c_client *i2c, u8 reg, u8 mask, u8 val) > +{ > + int ret; > + u8 status; > + > + ret = sii902x_read(i2c, reg, &status); > + if (ret) > + return ret; > + status &= ~mask; > + status |= val & mask; > + return sii902x_write(i2c, reg, status); > +} > + > +static int __sii902x_update_bits(struct i2c_client *i2c, u8 reg, u8 mask, > + u8 val) > +{ > + int ret; > + u8 status; > + > + ret = __sii902x_read(i2c, reg, &status); > + if (ret) > + return ret; > + status &= ~mask; > + status |= val & mask; > + return __sii902x_write(i2c, reg, status); > +} Dito. So now all read, write and rmw functions are duplicated. > static inline struct sii902x *bridge_to_sii902x(struct drm_bridge *bridge) > { > return container_of(bridge, struct sii902x, bridge); > @@ -115,9 +233,9 @@ static enum drm_connector_status > sii902x_connector_detect(struct drm_connector *connector, bool force) > { > struct sii902x *sii902x = connector_to_sii902x(connector); > - unsigned int status; > + u8 status; > > - regmap_read(sii902x->regmap, SII902X_INT_STATUS, &status); > + sii902x_read(sii902x->i2c, SII902X_INT_STATUS, &status); > > return (status & SII902X_PLUGGED_STATUS) ? > connector_status_connected : connector_status_disconnected; > @@ -135,41 +253,11 @@ static const struct drm_connector_funcs sii902x_connector_funcs = { > static int sii902x_get_modes(struct drm_connector *connector) > { > struct sii902x *sii902x = connector_to_sii902x(connector); > - struct regmap *regmap = sii902x->regmap; > u32 bus_format = MEDIA_BUS_FMT_RGB888_1X24; > - struct device *dev = &sii902x->i2c->dev; > - unsigned long timeout; > - unsigned int retries; > - unsigned int status; > struct edid *edid; > - int num = 0; > - int ret; > - > - ret = regmap_update_bits(regmap, SII902X_SYS_CTRL_DATA, > - SII902X_SYS_CTRL_DDC_BUS_REQ, > - SII902X_SYS_CTRL_DDC_BUS_REQ); > - if (ret) > - return ret; > + int num = 0, ret; > > - timeout = jiffies + > - msecs_to_jiffies(SII902X_I2C_BUS_ACQUISITION_TIMEOUT_MS); > - do { > - ret = regmap_read(regmap, SII902X_SYS_CTRL_DATA, &status); > - if (ret) > - return ret; > - } while (!(status & SII902X_SYS_CTRL_DDC_BUS_GRTD) && > - time_before(jiffies, timeout)); > - > - if (!(status & SII902X_SYS_CTRL_DDC_BUS_GRTD)) { > - dev_err(dev, "failed to acquire the i2c bus\n"); > - return -ETIMEDOUT; > - } > - > - ret = regmap_write(regmap, SII902X_SYS_CTRL_DATA, status); > - if (ret) > - return ret; > - > - edid = drm_get_edid(connector, sii902x->i2c->adapter); > + edid = drm_get_edid(connector, sii902x->i2cmux->adapter[0]); > drm_connector_update_edid_property(connector, edid); > if (edid) { > num = drm_add_edid_modes(connector, edid); > @@ -181,42 +269,6 @@ static int sii902x_get_modes(struct drm_connector *connector) > if (ret) > return ret; > > - /* > - * Sometimes the I2C bus can stall after failure to use the > - * EDID channel. Retry a few times to see if things clear > - * up, else continue anyway. > - */ > - retries = 5; > - do { > - ret = regmap_read(regmap, SII902X_SYS_CTRL_DATA, > - &status); > - retries--; > - } while (ret && retries); > - if (ret) > - dev_err(dev, "failed to read status (%d)\n", ret); > - > - ret = regmap_update_bits(regmap, SII902X_SYS_CTRL_DATA, > - SII902X_SYS_CTRL_DDC_BUS_REQ | > - SII902X_SYS_CTRL_DDC_BUS_GRTD, 0); > - if (ret) > - return ret; > - > - timeout = jiffies + > - msecs_to_jiffies(SII902X_I2C_BUS_ACQUISITION_TIMEOUT_MS); > - do { > - ret = regmap_read(regmap, SII902X_SYS_CTRL_DATA, &status); > - if (ret) > - return ret; > - } while (status & (SII902X_SYS_CTRL_DDC_BUS_REQ | > - SII902X_SYS_CTRL_DDC_BUS_GRTD) && > - time_before(jiffies, timeout)); > - > - if (status & (SII902X_SYS_CTRL_DDC_BUS_REQ | > - SII902X_SYS_CTRL_DDC_BUS_GRTD)) { > - dev_err(dev, "failed to release the i2c bus\n"); > - return -ETIMEDOUT; > - } > - > return num; > } > > @@ -237,20 +289,20 @@ static void sii902x_bridge_disable(struct drm_bridge *bridge) > { > struct sii902x *sii902x = bridge_to_sii902x(bridge); > > - regmap_update_bits(sii902x->regmap, SII902X_SYS_CTRL_DATA, > - SII902X_SYS_CTRL_PWR_DWN, > - SII902X_SYS_CTRL_PWR_DWN); > + sii902x_update_bits(sii902x->i2c, SII902X_SYS_CTRL_DATA, > + SII902X_SYS_CTRL_PWR_DWN, > + SII902X_SYS_CTRL_PWR_DWN); > } > > static void sii902x_bridge_enable(struct drm_bridge *bridge) > { > struct sii902x *sii902x = bridge_to_sii902x(bridge); > > - regmap_update_bits(sii902x->regmap, SII902X_PWR_STATE_CTRL, > - SII902X_AVI_POWER_STATE_MSK, > - SII902X_AVI_POWER_STATE_D(0)); > - regmap_update_bits(sii902x->regmap, SII902X_SYS_CTRL_DATA, > - SII902X_SYS_CTRL_PWR_DWN, 0); > + sii902x_update_bits(sii902x->i2c, SII902X_PWR_STATE_CTRL, > + SII902X_AVI_POWER_STATE_MSK, > + SII902X_AVI_POWER_STATE_D(0)); > + sii902x_update_bits(sii902x->i2c, SII902X_SYS_CTRL_DATA, > + SII902X_SYS_CTRL_PWR_DWN, 0); > } > > static void sii902x_bridge_mode_set(struct drm_bridge *bridge, > @@ -258,25 +310,25 @@ static void sii902x_bridge_mode_set(struct drm_bridge *bridge, > struct drm_display_mode *adj) > { > struct sii902x *sii902x = bridge_to_sii902x(bridge); > - struct regmap *regmap = sii902x->regmap; > - u8 buf[HDMI_INFOFRAME_SIZE(AVI)]; > + u8 buf[HDMI_INFOFRAME_SIZE(AVI) + 1]; Maybe this stuff should be a separate change? > struct hdmi_avi_infoframe frame; > int ret; > > - buf[0] = adj->clock; > - buf[1] = adj->clock >> 8; > - buf[2] = adj->vrefresh; > - buf[3] = 0x00; > - buf[4] = adj->hdisplay; > - buf[5] = adj->hdisplay >> 8; > - buf[6] = adj->vdisplay; > - buf[7] = adj->vdisplay >> 8; > - buf[8] = SII902X_TPI_CLK_RATIO_1X | SII902X_TPI_AVI_PIXEL_REP_NONE | > + buf[0] = SII902X_TPI_VIDEO_DATA; > + buf[1] = adj->clock; > + buf[2] = adj->clock >> 8; > + buf[3] = adj->vrefresh; > + buf[4] = 0x00; > + buf[5] = adj->hdisplay; > + buf[6] = adj->hdisplay >> 8; > + buf[7] = adj->vdisplay; > + buf[8] = adj->vdisplay >> 8; > + buf[9] = SII902X_TPI_CLK_RATIO_1X | SII902X_TPI_AVI_PIXEL_REP_NONE | > SII902X_TPI_AVI_PIXEL_REP_BUS_24BIT; > - buf[9] = SII902X_TPI_AVI_INPUT_RANGE_AUTO | > - SII902X_TPI_AVI_INPUT_COLORSPACE_RGB; > + buf[10] = SII902X_TPI_AVI_INPUT_RANGE_AUTO | > + SII902X_TPI_AVI_INPUT_COLORSPACE_RGB; > > - ret = regmap_bulk_write(regmap, SII902X_TPI_VIDEO_DATA, buf, 10); > + ret = sii902x_bulk_write(sii902x->i2c, buf, 11); > if (ret) > return; > > @@ -286,16 +338,17 @@ static void sii902x_bridge_mode_set(struct drm_bridge *bridge, > return; > } > > - ret = hdmi_avi_infoframe_pack(&frame, buf, sizeof(buf)); > + ret = hdmi_avi_infoframe_pack(&frame, buf + 1, sizeof(buf) - 1); > if (ret < 0) { > DRM_ERROR("failed to pack AVI infoframe: %d\n", ret); > return; > } > > + buf[0] = SII902X_TPI_AVI_INFOFRAME; > /* Do not send the infoframe header, but keep the CRC field. */ > - regmap_bulk_write(regmap, SII902X_TPI_AVI_INFOFRAME, > - buf + HDMI_INFOFRAME_HEADER_SIZE - 1, > - HDMI_AVI_INFOFRAME_SIZE + 1); > + sii902x_bulk_write(sii902x->i2c, > + buf + HDMI_INFOFRAME_HEADER_SIZE, > + HDMI_AVI_INFOFRAME_SIZE + 1); > } > > static int sii902x_bridge_attach(struct drm_bridge *bridge) > @@ -336,29 +389,13 @@ static const struct drm_bridge_funcs sii902x_bridge_funcs = { > .enable = sii902x_bridge_enable, > }; > > -static const struct regmap_range sii902x_volatile_ranges[] = { > - { .range_min = 0, .range_max = 0xff }, > -}; > - > -static const struct regmap_access_table sii902x_volatile_table = { > - .yes_ranges = sii902x_volatile_ranges, > - .n_yes_ranges = ARRAY_SIZE(sii902x_volatile_ranges), > -}; > - > -static const struct regmap_config sii902x_regmap_config = { > - .reg_bits = 8, > - .val_bits = 8, > - .volatile_table = &sii902x_volatile_table, > - .cache_type = REGCACHE_NONE, > -}; > - > static irqreturn_t sii902x_interrupt(int irq, void *data) > { > struct sii902x *sii902x = data; > - unsigned int status = 0; > + u8 status = 0; > > - regmap_read(sii902x->regmap, SII902X_INT_STATUS, &status); > - regmap_write(sii902x->regmap, SII902X_INT_STATUS, status); > + sii902x_read(sii902x->i2c, SII902X_INT_STATUS, &status); > + sii902x_write(sii902x->i2c, SII902X_INT_STATUS, status); > > if ((status & SII902X_HOTPLUG_EVENT) && sii902x->bridge.dev) > drm_helper_hpd_irq_event(sii902x->bridge.dev); > @@ -366,23 +403,111 @@ static irqreturn_t sii902x_interrupt(int irq, void *data) > return IRQ_HANDLED; > } > > +static int sii902x_i2c_bypass_select(struct i2c_mux_core *mux, u32 chan_id) > +{ > + struct sii902x *sii902x = i2c_mux_priv(mux); > + struct device *dev = &sii902x->i2c->dev; > + unsigned long timeout; > + u8 status; > + int ret; > + > + ret = __sii902x_update_bits(sii902x->i2c, SII902X_SYS_CTRL_DATA, > + SII902X_SYS_CTRL_DDC_BUS_REQ, > + SII902X_SYS_CTRL_DDC_BUS_REQ); > + > + timeout = jiffies + > + msecs_to_jiffies(SII902X_I2C_BUS_ACQUISITION_TIMEOUT_MS); > + do { > + ret = __sii902x_read(sii902x->i2c, SII902X_SYS_CTRL_DATA, > + &status); > + if (ret) > + return ret; > + } while (!(status & SII902X_SYS_CTRL_DDC_BUS_GRTD) && > + time_before(jiffies, timeout)); > + > + if (!(status & SII902X_SYS_CTRL_DDC_BUS_GRTD)) { > + dev_err(dev, "Failed to acquire the i2c bus\n"); > + return -ETIMEDOUT; > + } > + > + ret = __sii902x_write(sii902x->i2c, SII902X_SYS_CTRL_DATA, status); > + if (ret) > + return ret; > + return 0; > +} > + > +static int sii902x_i2c_bypass_deselect(struct i2c_mux_core *mux, u32 chan_id) > +{ > + struct sii902x *sii902x = i2c_mux_priv(mux); > + struct device *dev = &sii902x->i2c->dev; > + unsigned long timeout; > + unsigned int retries; > + u8 status; > + int ret; > + > + udelay(30); > + > + /* > + * Sometimes the I2C bus can stall after failure to use the > + * EDID channel. Retry a few times to see if things clear > + * up, else continue anyway. > + */ > + retries = 5; > + do { > + ret = __sii902x_read(sii902x->i2c, SII902X_SYS_CTRL_DATA, > + &status); > + retries--; > + } while (ret && retries); > + if (ret) { > + dev_err(dev, "failed to read status (%d)\n", ret); > + return ret; > + } > + > + ret = __sii902x_update_bits(sii902x->i2c, SII902X_SYS_CTRL_DATA, > + SII902X_SYS_CTRL_DDC_BUS_REQ | > + SII902X_SYS_CTRL_DDC_BUS_GRTD, 0); > + if (ret) > + return ret; > + > + timeout = jiffies + > + msecs_to_jiffies(SII902X_I2C_BUS_ACQUISITION_TIMEOUT_MS); > + do { > + ret = __sii902x_read(sii902x->i2c, SII902X_SYS_CTRL_DATA, > + &status); > + if (ret) > + return ret; > + } while (status & (SII902X_SYS_CTRL_DDC_BUS_REQ | > + SII902X_SYS_CTRL_DDC_BUS_GRTD) && > + time_before(jiffies, timeout)); > + > + if (status & (SII902X_SYS_CTRL_DDC_BUS_REQ | > + SII902X_SYS_CTRL_DDC_BUS_GRTD)) { > + dev_err(dev, "failed to release the i2c bus\n"); > + return -ETIMEDOUT; > + } > + > + return 0; > +} > + > static int sii902x_probe(struct i2c_client *client, > const struct i2c_device_id *id) > { > struct device *dev = &client->dev; > - unsigned int status = 0; > struct sii902x *sii902x; > - u8 chipid[4]; > + u8 chipid[4], status = 0; > int ret; > > + ret = i2c_check_functionality(client->adapter, I2C_FUNC_I2C); > + if (!ret) { > + dev_err(dev, "I2C adapter not suitable\n"); > + return -EIO; > + } > + > sii902x = devm_kzalloc(dev, sizeof(*sii902x), GFP_KERNEL); > if (!sii902x) > return -ENOMEM; > > sii902x->i2c = client; > - sii902x->regmap = devm_regmap_init_i2c(client, &sii902x_regmap_config); > - if (IS_ERR(sii902x->regmap)) > - return PTR_ERR(sii902x->regmap); > > sii902x->reset_gpio = devm_gpiod_get_optional(dev, "reset", > GPIOD_OUT_LOW); > @@ -394,14 +519,14 @@ static int sii902x_probe(struct i2c_client *client, > > sii902x_reset(sii902x); > > - ret = regmap_write(sii902x->regmap, SII902X_REG_TPI_RQB, 0x0); > + ret = sii902x_write(sii902x->i2c, SII902X_REG_TPI_RQB, 0x0); > if (ret) > return ret; > > - ret = regmap_bulk_read(sii902x->regmap, SII902X_REG_CHIPID(0), > - &chipid, 4); > + ret = sii902x_bulk_read(sii902x->i2c, SII902X_REG_CHIPID(0), > + chipid, 4); > if (ret) { > - dev_err(dev, "regmap_read failed %d\n", ret); > + dev_err(dev, "Can't read chipid (error = %d)\n", ret); > return ret; > } > > @@ -412,12 +537,12 @@ static int sii902x_probe(struct i2c_client *client, > } > > /* Clear all pending interrupts */ > - regmap_read(sii902x->regmap, SII902X_INT_STATUS, &status); > - regmap_write(sii902x->regmap, SII902X_INT_STATUS, status); > + sii902x_read(sii902x->i2c, SII902X_INT_STATUS, &status); > + sii902x_write(sii902x->i2c, SII902X_INT_STATUS, status); > > if (client->irq > 0) { > - regmap_write(sii902x->regmap, SII902X_INT_ENABLE, > - SII902X_HOTPLUG_EVENT); > + sii902x_write(sii902x->i2c, SII902X_INT_ENABLE, > + SII902X_HOTPLUG_EVENT); > > ret = devm_request_threaded_irq(dev, client->irq, NULL, > sii902x_interrupt, > @@ -433,6 +558,22 @@ static int sii902x_probe(struct i2c_client *client, > > i2c_set_clientdata(client, sii902x); > > + sii902x->i2cmux = i2c_mux_alloc(client->adapter, dev, > + 1, 0, I2C_MUX_GATE, > + sii902x_i2c_bypass_select, > + sii902x_i2c_bypass_deselect); > + if (!sii902x->i2cmux) { > + dev_err(dev, "failed to allocate I2C mux\n"); > + return -ENOMEM; > + } > + > + sii902x->i2cmux->priv = sii902x; > + ret = i2c_mux_add_adapter(sii902x->i2cmux, 0, 0, 0); > + if (ret) { > + dev_err(dev, "Couldn't add i2c mux adapter\n"); > + return ret; > + } > + > return 0; > } > > @@ -441,6 +582,9 @@ static int sii902x_remove(struct i2c_client *client) > { > struct sii902x *sii902x = i2c_get_clientdata(client); > > + if (sii902x->i2cmux) > + i2c_mux_del_adapters(sii902x->i2cmux); > + > drm_bridge_remove(&sii902x->bridge); > > return 0; Yours, Linus Walleij
