On Tue, Jul 11, 2017 at 03:30:09PM +0200, Hans Verkuil wrote: > From: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > This adds support for the DisplayPort CEC-Tunneling-over-AUX > feature that is part of the DisplayPort 1.3 standard. Hi Hans, Thank you for the patch, it looks great, I just have a few minor nits below. > > Unfortunately, not all DisplayPort/USB-C to HDMI adapters with a > chip that has this capability actually hook up the CEC pin, so > even though a CEC device is created, it may not actually work. Boo :( > > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > --- > drivers/gpu/drm/Kconfig | 10 ++ > drivers/gpu/drm/Makefile | 1 + > drivers/gpu/drm/drm_dp_cec.c | 308 +++++++++++++++++++++++++++++++++++++++++++ > include/drm/drm_dp_helper.h | 24 ++++ > 4 files changed, 343 insertions(+) > create mode 100644 drivers/gpu/drm/drm_dp_cec.c > > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig > index 83cb2a88c204..1f2708df5c4e 100644 > --- a/drivers/gpu/drm/Kconfig > +++ b/drivers/gpu/drm/Kconfig > @@ -120,6 +120,16 @@ config DRM_LOAD_EDID_FIRMWARE > default case is N. Details and instructions how to build your own > EDID data are given in Documentation/EDID/HOWTO.txt. > > +config DRM_DP_CEC > + bool "Enable DisplayPort CEC-Tunneling-over-AUX HDMI support" > + select CEC_CORE > + help > + Choose this option if you want to enable HDMI CEC support for > + DisplayPort/USB-C to HDMI adapters. > + > + Note: not all adapters support this feature, and even for those > + that do support this they often do not hook up the CEC pin. > + > config DRM_TTM > tristate > depends on DRM && MMU > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile > index 24a066e1841c..c6552c62049e 100644 > --- a/drivers/gpu/drm/Makefile > +++ b/drivers/gpu/drm/Makefile > @@ -40,6 +40,7 @@ drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o > drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o > drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o > drm_kms_helper-$(CONFIG_DRM_DP_AUX_CHARDEV) += drm_dp_aux_dev.o > +drm_kms_helper-$(CONFIG_DRM_DP_CEC) += drm_dp_cec.o > > obj-$(CONFIG_DRM_KMS_HELPER) += drm_kms_helper.o > obj-$(CONFIG_DRM_DEBUG_MM_SELFTEST) += selftests/ > diff --git a/drivers/gpu/drm/drm_dp_cec.c b/drivers/gpu/drm/drm_dp_cec.c > new file mode 100644 > index 000000000000..7f2e298d45c0 > --- /dev/null > +++ b/drivers/gpu/drm/drm_dp_cec.c > @@ -0,0 +1,308 @@ > +/* > + * DisplayPort CEC-Tunneling-over-AUX support > + * > + * Copyright 2017 Cisco Systems, Inc. and/or its affiliates. All rights reserved. > + * > + * This program is free software; you may redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; version 2 of the License. > + * > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, > + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF > + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND > + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS > + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN > + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN > + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE > + * SOFTWARE. > + */ > + > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/slab.h> > +#include <drm/drm_dp_helper.h> > +#include <media/cec.h> > + > +/* > + * Unfortunately it turns out that we have a chicken-and-egg situation > + * here. Quite a few active (mini-)DP-to-HDMI or USB-C-to-HDMI adapters > + * have a converter chip that supports CEC-Tunneling-over-AUX (usually the > + * Parade PS176), but they do not wire up the CEC pin, thus making CEC > + * useless. > + * > + * Sadly there is no way for this driver to know this. What happens is > + * that a /dev/cecX device is created that is isolated and unable to see > + * any of the other CEC devices. Quite literally the CEC wire is cut > + * (or in this case, never connected in the first place). > + * > + * I suspect that the reason so few adapters support this is that this > + * tunneling protocol was never supported by any OS. So there was no > + * easy way of testing it, and no incentive to correctly wire up the > + * CEC pin. > + * > + * Hopefully by creating this driver it will be easier for vendors to > + * finally fix their adapters and test the CEC functionality. > + * > + * I keep a list of known working adapters here: > + * > + * https://hverkuil.home.xs4all.nl/cec-status.txt > + * > + * Please mail me (hverkuil@xxxxxxxxx) if you find an adapter that works > + * and is not yet listed there. According to the schematics, the Google USB-C -> HDMI adapter[1] has CEC wired up. [1]- https://store.google.com/product/usb_type_c_to_hdmi_adapter > + */ > + > +/** > + * DOC: dp cec helpers > + * > + * These functions take care of supporting the CEC-Tunneling-over-AUX > + * feature of DisplayPort-to-HDMI adapters. > + */ > + > +static int drm_dp_cec_adap_enable(struct cec_adapter *adap, bool enable) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + ssize_t err = 0; > + > + if (enable) > + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, > + DP_CEC_TUNNELING_ENABLE); > + else > + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, 0); nit: The pattern for this type of thing is usually, u32 val = 0; if (enable) val = DP_CEC_TUNNELING_ENABLE; err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); > + return (enable && err < 0) ? err : 0; > +} > + > +static int drm_dp_cec_adap_log_addr(struct cec_adapter *adap, u8 addr) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + u8 mask[2] = { 0x00, 0x80 }; > + ssize_t err; > + > + if (addr != CEC_LOG_ADDR_INVALID) { Save yourself a bit of work and do: if (addr == CEC_LOG_ADDR_INVALID) return 0; > + u16 la_mask = adap->log_addrs.log_addr_mask; > + > + la_mask |= 0x8000 | (1 << addr); What's the 0x8000? Can you make it a little more clear by doing: la_mask |= 1 << SOME_DESCRIPTIVE_NAME | (1 << addr); > + mask[0] = la_mask & 0xff; > + mask[1] = la_mask >> 8; > + } > + err = drm_dp_dpcd_write(aux, DP_CEC_LOGICAL_ADDRESS_MASK, mask, 2); > + return (addr != CEC_LOG_ADDR_INVALID && err < 0) ? err : 0; > +} > + > +static int drm_dp_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, > + u32 signal_free_time, struct cec_msg *msg) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + unsigned int retries = attempts - 1; unsigned int retries = min(5, attempts - 1); > + ssize_t err; > + > + err = drm_dp_dpcd_write(aux, DP_CEC_TX_MESSAGE_BUFFER, > + msg->msg, msg->len); > + if (err < 0) > + return err; > + > + if (retries > 5) > + retries = 5; > + err = drm_dp_dpcd_writeb(aux, DP_CEC_TX_MESSAGE_INFO, > + (msg->len - 1) | (retries << 4) | > + DP_CEC_TX_MESSAGE_SEND); > + return err < 0 ? err : 0; > +} > + > +static int drm_dp_cec_adap_monitor_all_enable(struct cec_adapter *adap, > + bool enable) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + ssize_t err; > + u8 val; > + > + if (!(adap->capabilities & CEC_CAP_MONITOR_ALL)) > + return 0; > + > + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CONTROL, &val); > + if (err >= 0) { > + if (enable) > + val |= DP_CEC_SNOOPING_ENABLE; > + else > + val &= ~DP_CEC_SNOOPING_ENABLE; > + err = drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_CONTROL, val); > + } > + return (enable && err < 0) ? err : 0; > +} > + > +static void drm_dp_cec_adap_status(struct cec_adapter *adap, > + struct seq_file *file) > +{ > + struct drm_dp_aux *aux = cec_get_drvdata(adap); > + u8 buf[DP_AUX_MAX_PAYLOAD_BYTES]; > + u8 hw_rev; > + > + if (drm_dp_dpcd_read(aux, DP_BRANCH_OUI, > + buf, sizeof(buf)) != sizeof(buf)) > + return; > + hw_rev = buf[9]; > + buf[9] = 0; > + seq_printf(file, "OUI: %02x-%02x-%02x\n", > + buf[0], buf[1], buf[2]); > + seq_printf(file, "ID: %s\n", buf + 3); > + seq_printf(file, "HW Rev: %d.%d\n", hw_rev >> 4, hw_rev & 0xf); > + /* > + * Show this both in decimal and hex: at least one vendor > + * always reports this in hex. > + */ > + seq_printf(file, "FW/SW Rev: %d.%d (0x%02x.0x%02x)\n", > + buf[10], buf[11], buf[10], buf[11]); > +} > + > +static const struct cec_adap_ops drm_dp_cec_adap_ops = { > + .adap_enable = drm_dp_cec_adap_enable, > + .adap_log_addr = drm_dp_cec_adap_log_addr, > + .adap_transmit = drm_dp_cec_adap_transmit, > + .adap_monitor_all_enable = drm_dp_cec_adap_monitor_all_enable, > + .adap_status = drm_dp_cec_adap_status, > +}; > + > +static int drm_dp_cec_received(struct drm_dp_aux *aux) > +{ > + struct cec_adapter *adap = aux->cec_adap; > + struct cec_msg msg; > + u8 rx_msg_info; > + ssize_t err; > + > + err = drm_dp_dpcd_readb(aux, DP_CEC_RX_MESSAGE_INFO, &rx_msg_info); > + if (err < 0) > + return err; > + if (!(rx_msg_info & DP_CEC_RX_MESSAGE_ENDED)) > + return 0; > + msg.len = (rx_msg_info & DP_CEC_RX_MESSAGE_LEN_MASK) + 1; > + err = drm_dp_dpcd_read(aux, DP_CEC_RX_MESSAGE_BUFFER, msg.msg, msg.len); > + if (err < 0) > + return err; > + cec_received_msg(adap, &msg); > + return 0; > +} > + > +static int drm_dp_cec_handle_irq(struct drm_dp_aux *aux) > +{ > + struct cec_adapter *adap = aux->cec_adap; > + u8 flags; > + ssize_t err; > + > + err = drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, &flags); > + if (err < 0) > + return err; > + > + if (flags & DP_CEC_RX_MESSAGE_INFO_VALID) > + drm_dp_cec_received(aux); > + > + if (flags & DP_CEC_TX_MESSAGE_SENT) > + cec_transmit_attempt_done(adap, CEC_TX_STATUS_OK); > + else if (flags & DP_CEC_TX_LINE_ERROR) > + cec_transmit_attempt_done(adap, CEC_TX_STATUS_ERROR | > + CEC_TX_STATUS_MAX_RETRIES); > + else if (flags & > + (DP_CEC_TX_ADDRESS_NACK_ERROR | DP_CEC_TX_DATA_NACK_ERROR)) > + cec_transmit_attempt_done(adap, CEC_TX_STATUS_NACK | > + CEC_TX_STATUS_MAX_RETRIES); > + drm_dp_dpcd_writeb(aux, DP_CEC_TUNNELING_IRQ_FLAGS, flags); > + return 0; > +} > + > +/** > + * drm_dp_cec_irq() - handle CEC interrupt, if any > + * @aux: DisplayPort AUX channel > + * > + * Should be called when handling an IRQ_HPD request. If CEC-tunneling-over-AUX > + * is present, then it will check for a CEC_IRQ and handle it accordingly. > + * > + * Returns true if an interrupt was handled successfully or false otherwise. > + */ > +bool drm_dp_cec_irq(struct drm_dp_aux *aux) > +{ > + int attempts = 4; > + bool handled = false; > + > + if (!aux->cec_adap) > + return false; > + > + while (attempts--) { nit: this seems more natural as a for loop: for (int attempts = 5; attempts > 0; attempts--) > + u8 cec_irq; > + int ret; > + > + ret = drm_dp_dpcd_readb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, > + &cec_irq); > + if (ret < 0 || !(cec_irq & DP_CEC_IRQ)) > + break; > + > + if (!drm_dp_cec_handle_irq(aux)) > + handled = true; > + > + ret = drm_dp_dpcd_writeb(aux, DP_DEVICE_SERVICE_IRQ_VECTOR_ESI1, > + DP_CEC_IRQ); > + if (ret < 0) > + break; > + } > + return handled; > +} > +EXPORT_SYMBOL(drm_dp_cec_irq); > + > +/** > + * drm_dp_cec_configure_adapter() - configure the CEC adapter > + * @aux: DisplayPort AUX channel > + * @name: name of the CEC device > + * @parent: parent device > + * > + * Checks if this is a DisplayPort-to-HDMI adapter that supports > + * CEC-tunneling-over-AUX, and if so it creates a CEC device. > + * > + * If a CEC device was already created, then check if the capabilities > + * have changed. If not, then do nothing. Otherwise destroy the old > + * CEC device and create a new CEC device. > + * > + * This can happen when one DP-to-HDMI adapter is disconnected and > + * replaced by another adapter with different CEC capabilities. > + * > + * Returns 0 on success or a negative error code on failure. > + */ > +int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux, const char *name, > + struct device *parent) > +{ > + u32 cec_caps = CEC_CAP_LOG_ADDRS | CEC_CAP_TRANSMIT | > + CEC_CAP_PASSTHROUGH | CEC_CAP_RC | CEC_CAP_NEEDS_HPD; > + unsigned int num_las = 1; > + int err; > + u8 cap; > + > + if (drm_dp_dpcd_readb(aux, DP_CEC_TUNNELING_CAPABILITY, &cap) != 1 || > + !(cap & DP_CEC_TUNNELING_CAPABLE)) { > + cec_unregister_adapter(aux->cec_adap); > + aux->cec_adap = NULL; > + return -ENODEV; > + } > + > + if (cap & DP_CEC_SNOOPING_CAPABLE) > + cec_caps |= CEC_CAP_MONITOR_ALL; > + if (cap & DP_CEC_MULTIPLE_LA_CAPABLE) > + num_las = CEC_MAX_LOG_ADDRS; > + > + if (!IS_ERR_OR_NULL(aux->cec_adap)) { > + if (aux->cec_adap->capabilities == cec_caps && > + aux->cec_adap->available_log_addrs == num_las) > + return 0; > + cec_unregister_adapter(aux->cec_adap); > + } > + > + aux->cec_adap = cec_allocate_adapter(&drm_dp_cec_adap_ops, > + aux, name, cec_caps, num_las); > + if (IS_ERR(aux->cec_adap)) { > + err = PTR_ERR(aux->cec_adap); > + aux->cec_adap = NULL; > + return err; > + } > + err = cec_register_adapter(aux->cec_adap, parent); > + if (err) { > + cec_delete_adapter(aux->cec_adap); > + aux->cec_adap = NULL; > + } > + return err; > +} > +EXPORT_SYMBOL(drm_dp_cec_configure_adapter); > diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h > index b17476a6909c..0e236dd40b42 100644 > --- a/include/drm/drm_dp_helper.h > +++ b/include/drm/drm_dp_helper.h > @@ -952,6 +952,8 @@ struct drm_dp_aux_msg { > size_t size; > }; > > +struct cec_adapter; > + > /** > * struct drm_dp_aux - DisplayPort AUX channel > * @name: user-visible name of this AUX channel and the I2C-over-AUX adapter > @@ -1010,6 +1012,10 @@ struct drm_dp_aux { > * @i2c_defer_count: Counts I2C DEFERs, used for DP validation. > */ > unsigned i2c_defer_count; > + /** > + * @cec_adap: the CEC adapter for CEC-Tunneling-over-AUX support. > + */ > + struct cec_adapter *cec_adap; > }; > > ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, > @@ -1132,4 +1138,22 @@ drm_dp_has_quirk(const struct drm_dp_desc *desc, enum drm_dp_quirk quirk) > return desc->quirks & BIT(quirk); > } > > +#ifdef CONFIG_DRM_DP_CEC > +bool drm_dp_cec_irq(struct drm_dp_aux *aux); > +int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux, const char *name, > + struct device *parent); > +#else > +static inline bool drm_dp_cec_irq(struct drm_dp_aux *aux) > +{ > + return false; > +} > + > +static inline int drm_dp_cec_configure_adapter(struct drm_dp_aux *aux, > + const char *name, > + struct device *parent) > +{ > + return -ENODEV; > +} > +#endif > + > #endif /* _DRM_DP_HELPER_H_ */ > -- > 2.11.0 > > _______________________________________________ > dri-devel mailing list > dri-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Sean Paul, Software Engineer, Google / Chromium OS
