linux-kernel - Re: [PATCH V2] drm/bridge: adv7533: Fix adv7533_mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAN6tsi5N8iir-nNH2SV6-jJizgg92cJEPb-0BoSdprsjWQfG7A@mail.gmail.com>
Date:   Mon, 20 Mar 2023 11:05:44 +0100
From:   Robert Foss <rfoss@...nel.org>
To:     Adam Ford <aford173@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, dmitry.baryshkov@...aro.org,
        aford@...conembedded.com, Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] drm/bridge: adv7533: Fix adv7533_mode_valid for
 adv7533 and adv7535

On Sun, Mar 19, 2023 at 1:55 PM Adam Ford <aford173@...il.com> 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@...nel.org>
> Signed-off-by: Adam Ford <aford173@...il.com>
> ---
>
> 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.