linux-kernel - Re: [PATCH] drm/panel: simple: Fix AUO G121EAN01 panel timings according to the docs

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Date:   Mon, 14 Aug 2023 14:37:05 +0200
From:   Neil Armstrong <neil.armstrong@...aro.org>
To:     Luca Ceresoli <luca.ceresoli@...tlin.com>,
        dri-devel@...ts.freedesktop.org
Cc:     Sam Ravnborg <sam@...nborg.org>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Sebastian Reichel <sebastian.reichel@...labora.com>,
        linux-kernel@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Subject: Re: [PATCH] drm/panel: simple: Fix AUO G121EAN01 panel timings
 according to the docs

On 04/08/2023 17:12, Luca Ceresoli wrote:
> Commit 03e909acd95a ("drm/panel: simple: Add support for AUO G121EAN01.4
> panel") added support for this panel model, but the timings it implements
> are very different from what the datasheet describes. I checked both the
> G121EAN01.0 datasheet from [0] and the G121EAN01.4 one from [1] and they
> all have the same timings: for example the LVDS clock typical value is 74.4
> MHz, not 66.7 MHz as implemented.
> 
> Replace the timings with the ones from the documentation. These timings
> have been tested and the clock frequencies verified with an oscilloscope to
> ensure they are correct.
> 
> Also use struct display_timing instead of struct drm_display_mode in order
> to also specify the minimum and maximum values.
> 
> [0] https://embedded.avnet.com/product/g121ean01-0/
> [1] https://embedded.avnet.com/product/g121ean01-4/
> 
> Fixes: 03e909acd95a ("drm/panel: simple: Add support for AUO G121EAN01.4 panel")
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
> ---
>   drivers/gpu/drm/panel/panel-simple.c | 24 ++++++++++++------------
>   1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
> index 701013b3ad13..56854f78441e 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -999,21 +999,21 @@ static const struct panel_desc auo_g104sn02 = {
>   	.connector_type = DRM_MODE_CONNECTOR_LVDS,
>   };
>   
> -static const struct drm_display_mode auo_g121ean01_mode = {
> -	.clock = 66700,
> -	.hdisplay = 1280,
> -	.hsync_start = 1280 + 58,
> -	.hsync_end = 1280 + 58 + 8,
> -	.htotal = 1280 + 58 + 8 + 70,
> -	.vdisplay = 800,
> -	.vsync_start = 800 + 6,
> -	.vsync_end = 800 + 6 + 4,
> -	.vtotal = 800 + 6 + 4 + 10,
> +static const struct display_timing auo_g121ean01_timing = {
> +	.pixelclock = { 60000000, 74400000, 90000000 },
> +	.hactive = { 1280, 1280, 1280 },
> +	.hfront_porch = { 20, 50, 100 },
> +	.hback_porch = { 20, 50, 100 },
> +	.hsync_len = { 30, 100, 200 },
> +	.vactive = { 800, 800, 800 },
> +	.vfront_porch = { 2, 10, 25 },
> +	.vback_porch = { 2, 10, 25 },
> +	.vsync_len = { 4, 18, 50 },
>   };
>   
>   static const struct panel_desc auo_g121ean01 = {
> -	.modes = &auo_g121ean01_mode,
> -	.num_modes = 1,
> +	.timings = &auo_g121ean01_timing,
> +	.num_timings = 1,
>   	.bpc = 8,
>   	.size = {
>   		.width = 261,

Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>