linux-kernel - Re: [PATCH v3 2/5] drm/mipi-dbi: Remove mipi_dbi_machine_little

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Date: Mon, 3 Jun 2024 23:31:03 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: noralf@...nnes.org
Cc: Neil Armstrong <neil.armstrong@...aro.org>, 
	Jessica Zhang <quic_jesszhan@...cinc.com>, Sam Ravnborg <sam@...nborg.org>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	David Lechner <david@...hnology.com>, dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Kamlesh Gurudasani <kamlesh.gurudasani@...il.com>, 
	Tommaso Merciai <tommaso.merciai@...rulasolutions.com>
Subject: Re: [PATCH v3 2/5] drm/mipi-dbi: Remove
 mipi_dbi_machine_little_endian()

On Mon, Jun 03, 2024 at 01:21:33PM +0200, Noralf Trønnes via B4 Relay wrote:
> From: Noralf Trønnes <noralf@...nnes.org>
> 
> mipi_dbi_machine_little_endian() should really have been called
> mipi_dbi_framebuffer_little_endian() because that's the function it
> performs. When I added support for these SPI displays I thought that the
> framebuffers on big endian machines were also big endian, but I have
> later learned that this is not the case. There's a bit in the fourcc code
> that controls this: DRM_FORMAT_BIG_ENDIAN.
> 
> Just remove the function to avoid confusion. We can add big endian support
> later should the need arise and we have hardware to test on.
> 
> Instead of just amending the docs, expand it to explain the endianness
> handling.
> 
> Signed-off-by: Noralf Trønnes <noralf@...nnes.org>
> ---
>  drivers/gpu/drm/drm_mipi_dbi.c | 35 +++++++++++++++++++----------------
>  1 file changed, 19 insertions(+), 16 deletions(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>


-- 
With best wishes
Dmitry