linux-kernel - Re: [PATCH 3/3] drm/tinydrm: Fix setting of the column/page end addresses.

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Message-ID: <6cc67180-c844-566a-cb59-b06e9e2ff72a@tronnes.org>
Date:   Sat, 27 Oct 2018 18:13:44 +0200
From:   Noralf Trønnes <noralf@...nnes.org>
To:     Eric Anholt <eric@...olt.net>, dri-devel@...ts.freedesktop.org,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Heiner Kallweit <hkallweit1@...il.com>
Subject: Re: [PATCH 3/3] drm/tinydrm: Fix setting of the column/page end
 addresses.


Den 24.10.2018 20.43, skrev Eric Anholt:
> If the clipped dirty region's x/y happened to align to 256, we would
> have set the top 8 bits wrong.  Noticed by inspection, not by
> reproducing a bug.
>
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---

Good catch.
Reviewed-by: Noralf Trønnes <noralf@...nnes.org>

>   drivers/gpu/drm/tinydrm/mipi-dbi.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/tinydrm/mipi-dbi.c b/drivers/gpu/drm/tinydrm/mipi-dbi.c
> index cb3441e51d5f..1bb870021f6e 100644
> --- a/drivers/gpu/drm/tinydrm/mipi-dbi.c
> +++ b/drivers/gpu/drm/tinydrm/mipi-dbi.c
> @@ -240,10 +240,10 @@ static int mipi_dbi_fb_dirty(struct drm_framebuffer *fb,
>   
>   	mipi_dbi_command(mipi, MIPI_DCS_SET_COLUMN_ADDRESS,
>   			 (clip.x1 >> 8) & 0xFF, clip.x1 & 0xFF,
> -			 (clip.x2 >> 8) & 0xFF, (clip.x2 - 1) & 0xFF);
> +			 ((clip.x2 - 1) >> 8) & 0xFF, (clip.x2 - 1) & 0xFF);
>   	mipi_dbi_command(mipi, MIPI_DCS_SET_PAGE_ADDRESS,
>   			 (clip.y1 >> 8) & 0xFF, clip.y1 & 0xFF,
> -			 (clip.y2 >> 8) & 0xFF, (clip.y2 - 1) & 0xFF);
> +			 ((clip.y2 - 1) >> 8) & 0xFF, (clip.y2 - 1) & 0xFF);
>   
>   	ret = mipi_dbi_command_buf(mipi, MIPI_DCS_WRITE_MEMORY_START, tr,
>   				(clip.x2 - clip.x1) * (clip.y2 - clip.y1) * 2);