On Sun, Mar 12, 2023 at 2:10 AM Dmitry Baryshkov
<dmitry.baryshkov@xxxxxxxxxx> wrote:
>
> On 12/03/2023 01:10, Adam Ford wrote:
> > When dynamically switching lanes was removed, the intent of the code
> > was to check to make sure that higher speed items used 4 lanes, but
> > it had the unintended consequence of removing the slower speeds for
> > 4-lane users.
> >
> > This attempts to remedy this by doing a check to see that the
> > max frequency doesn't exceed the chip limit, and a second
> > check to make sure that the max bit-rate doesn't exceed the
> > number of lanes * max bit rate / lane.
> >
> > Fixes: 9a0cdcd6649b ("drm/bridge: adv7533: remove dynamic lane switching from adv7533 bridge")
> >
>
> Please remove the empty line here. There should be no empty lines
> between the tags
>
>
> > Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
> >
> > diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > index fdfeadcefe80..10a112d36945 100644
> > --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> > @@ -103,13 +103,9 @@ void adv7533_dsi_power_off(struct adv7511 *adv)
> > enum drm_mode_status adv7533_mode_valid(struct adv7511 *adv,
> > const struct drm_display_mode *mode)
> > {
> > - int lanes;
> > + unsigned long max_lane_freq;
> > struct mipi_dsi_device *dsi = adv->dsi;
> > -
> > - if (mode->clock > 80000)
> > - lanes = 4;
> > - else
> > - lanes = 3;
> > + u8 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> >
> > /*
> > * TODO: add support for dynamic switching of lanes
>
> Drop the comment please. It makes little sense with your new implementation.
>
> > @@ -117,8 +113,16 @@ enum drm_mode_status adv7533_mode_valid(struct adv7511 *adv,
> > * out the modes which shall need different number of lanes
> > * than what was configured in the device tree.
> > */
> > - if (lanes != dsi->lanes)
> > - return MODE_BAD;
> > +
> > + /* Check max clock for either 7533 or 7535 */
> > + if (mode->clock > (adv->type == ADV7533 ? 80000 : 148500))
> > + return MODE_CLOCK_HIGH;
> > +
> > + /* Check max clock for each lane */
> > + max_lane_freq = (adv->type == ADV7533 ? 800000 : 891000);
> > +
> > + if (mode->clock * bpp > max_lane_freq * adv->num_dsi_lanes)
> > + return MODE_CLOCK_HIGH;
> >
> > return MODE_OK;
> > }
>
> --
> With best wishes
> Dmitry
>
With Dmitrys feedback, feel free to add my Reviewed-by.
