On Sun, Mar 19, 2023 at 1:55 PM Adam Ford <aford173@xxxxxxxxx> 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")
> Reviewed-by: Robert Foss <rfoss@xxxxxxxxxx>
> Signed-off-by: Adam Ford <aford173@xxxxxxxxx>
> ---
>
> V2: Fix whitespace in comment
> Remove TODO comment
> Add R-B from Robert.
>
> diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> index fdfeadcefe80..7e3e56441aed 100644
> --- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
> +++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
> @@ -103,22 +103,19 @@ 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;
> + u8 bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
>
> - if (mode->clock > 80000)
> - lanes = 4;
> - else
> - lanes = 3;
> -
> - /*
> - * TODO: add support for dynamic switching of lanes
> - * by using the bridge pre_enable() op . Till then filter
> - * 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;
> }
> --
> 2.34.1
>
Applied, thanks!
Repo: https://cgit.freedesktop.org/drm/drm-misc/
Rob.
