Hi Emil,
On Fri, 3 Jun 2016 10:38:49 +0100
Emil Velikov <emil.l.velikov@xxxxxxxxx> wrote:
> Hi Boris.
>
> On 2 June 2016 at 16:00, Boris Brezillon
> <boris.brezillon@xxxxxxxxxxxxxxxxxx> wrote:
>
> > +static void sii902x_reset(struct sii902x *sii902x)
> > +{
> > + if (!sii902x->reset_gpio)
> > + return;
> > +
> This is wrong (reset_gpio is err_ptr) although we can/should nuke it
> all together. See below for reasoning.
>
> > + gpiod_set_value(sii902x->reset_gpio, 1);
> > +
> > + msleep(100);
> Ouch that is some juicy number. Can we get a comment with
> reasoning/origin of it ?
As already explained to Maxime, I just don't know why this is needed,
simply because I don't have access to the datasheet and I just based my
implementation on another driver.
I can add a comment stating that this was extracted from another
implementation, but with no explanation on why this is needed.
Meng, do you have any information about startup-time, or something like
that?
>
> ...
>
> > +static void sii902x_bridge_mode_set(struct drm_bridge *bridge,
> > + struct drm_display_mode *mode,
> > + struct drm_display_mode *adj)
> > +{
> > + u8 buf[HDMI_INFOFRAME_HEADER_SIZE + HDMI_AVI_INFOFRAME_SIZE];
> HDMI_INFOFRAME_SIZE(AVI) seems shorter/easier to head imho.
Yep.
>
> > + struct sii902x *sii902x = bridge_to_sii902x(bridge);
> > + struct regmap *regmap = sii902x->regmap;
> > + 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] = SIL902X_TPI_CLK_RATIO_1X | SIL902X_TPI_AVI_PIXEL_REP_NONE |
> > + SIL902X_TPI_AVI_PIXEL_REP_BUS_24BIT;
> > + buf[9] = SIL902X_TPI_AVI_INPUT_RANGE_AUTO |
> > + SIL902X_TPI_AVI_INPUT_COLORSPACE_RGB;
> > +
> Since all of the contents are cleared in hdmi_avi_infoframe_pack, move
> the above into const video_data[] ?
Something like
const video_data[] = {
adj->clock,
adj->clock >> 8,
...
};
So we would have 2 buffers on the stack? Is this really useful?
>
> > + ret = regmap_bulk_write(regmap, SIL902X_TPI_VIDEO_DATA, buf, 10);
> ... and use ARRAY_SIZE(video_data) over the hardcoded 10 ?
>
> ...
>
> > +static int sii902x_bridge_attach(struct drm_bridge *bridge)
> > +{
> > + struct sii902x *sii902x = bridge_to_sii902x(bridge);
> > + struct drm_device *drm = bridge->dev;
> > + int ret;
> > +
> > + drm_connector_helper_add(&sii902x->connector,
> > + &sii902x_connector_helper_funcs);
> > +
> > + if (!drm_core_check_feature(drm, DRIVER_ATOMIC)) {
> > + dev_err(&sii902x->i2c->dev,
> > + "sii902x driver is only compatible with DRM devices supporting atomic updates");
> > + return -ENOTSUPP;
> > + }
> > +
> > + ret = drm_connector_init(drm, &sii902x->connector,
> > + &sii902x_connector_funcs,
> > + DRM_MODE_CONNECTOR_HDMIA);
> Side note: seems like most places in DRM do not check the return value
> (~80 vs ~20). I wonder how badly/likely are things to explode.
Yep. I tend to always check return code, but if you say it's useless
(and error-prone) I can remove it.
>
> ...
>
> > +static int sii902x_probe(struct i2c_client *client,
> > + const struct i2c_device_id *id)
> > +{
> ...
>
> > +
> > + sii902x->reset_gpio = devm_gpiod_get_optional(dev, "reset",
> > + GPIOD_OUT_LOW);
> > + if (IS_ERR(sii902x->reset_gpio))
> > + dev_warn(dev, "Failed to retrieve/request reset gpio: %ld\n",
> > + PTR_ERR(sii902x->reset_gpio));
> > +
> Documentation says "Required" not optional. The above should be
> updated and one should error out if missing, right ?
Actually I was asked to make it optional, just forgot to update the
documentation. This being said, devm_gpiod_get_optional() returns NULL
if the property is not defined in the DT and an error code if the error
comes from the GPIO layer, so I should just switch back to dev_err()
and return the error code here.
This would make the test in sii902x_reset() valid again.
>
> ...
>
> > +
> > + if (client->irq > 0) {
> I was always confused which is the correct way to check this >= 0 vs >
> 0. DRM has both :-\
> Do you have any suggestions, should be 'mass convert' DRM to use only
> one of the two ?
Not sure 0 is a valid irq number anymore, so I don't think it's really
important, but I can change it if you want.
Regards,
Boris
--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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