linux-kernel - Re: [PATCH] drm/meson: fix TMDS clock filtering for DMT monitors

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Date:   Mon, 25 Mar 2019 11:20:40 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     daniel@...ll.ch
Cc:     dri-devel@...ts.freedesktop.org, linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Maxime Jourdan <mjourdan@...libre.com>
Subject: Re: [PATCH] drm/meson: fix TMDS clock filtering for DMT monitors

On 20/03/2019 09:11, Neil Armstrong wrote:
> DMT monitors does not necessarely report a maximum TMDS clock
> in a VSDB EDID extension.
> 
> In this case, all modes are wrongly rejected, including
> the DRM fallback EDID.
> 
> This patch only rejects modes whith clock > max_tmds_clock if
> the max_tmds_clock is specified. This will only reject
> 4:2:0 HDMI2.0 modes, who reports a clock > max_tmds_clock.
> 
> Reported-by: Maxime Jourdan <mjourdan@...libre.com>
> Fixes: d7d8fb7046b6 ("drm/meson: add HDMI div40 TMDS mode")
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> ---
>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index e28814f4ea6c..563953ec6ad0 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -569,7 +569,8 @@ dw_hdmi_mode_valid(struct drm_connector *connector,
>  	DRM_DEBUG_DRIVER("Modeline " DRM_MODE_FMT "\n", DRM_MODE_ARG(mode));
>  
>  	/* If sink max TMDS clock, we reject the mode */
> -	if (mode->clock > connector->display_info.max_tmds_clock)
> +	if (connector->display_info.max_tmds_clock &&
> +	    mode->clock > connector->display_info.max_tmds_clock)
>  		return MODE_BAD;
>  
>  	/* Check against non-VIC supported modes */
> 

Applied to drm-misc-fixes