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From: Sidharth Saha <ssaha2000@gmail.com>
To: Matheus Alves de Almeida <matheus.aalmeida@inf.ufrgs.br>,
	Louis Chauvet <louis.chauvet@bootlin.com>,
	Haneen Mohammed <hamohammed.sa@gmail.com>,
	Simona Vetter <simona@ffwll.ch>,
	Melissa Wen <melissa.srw@gmail.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/5] drm/vkms: make argb_u16_to_RGB565 round resulting values
Date: Sat, 7 Nov 2026 20:12:29 -0700	[thread overview]
Message-ID: <097af97e-4d8a-477e-8eae-89f3fe485dc1@gmail.com> (raw)
In-Reply-To: <20260928005301.367977-2-matheus.aalmeida@inf.ufrgs.br>

Hi Matheus,

I wrote a KUnit test for argb_u16_to_RGB565() covering zero and max
values, the channel midpoint (0x8000 -> 16/32/16), the 0->1 rounding
step for a 5-bit channel (1057 -> 0, 1058 -> 1), and distinct values
per channel to catch channel placement.

Without this patch, the midpoint, above-step and distinct cases fail
(e.g. green comes out 31 instead of 32, i.e. truncated). With it, all
six cases pass.

Tested-by: Sidharth Saha ssaha2000@gmail.com

Since this rounding fix was lost once before in a refactor, I'm happy
to send the test as a follow-up patch once this series lands, or you're
welcome to fold it into a v2 if that's easier.

Thanks,
Sidharth

On 9/27/2026 5:52 PM, Matheus Alves de Almeida wrote:
> Currently, argb_u16_to_RGB565() truncates the resulting channel values.


  reply	other threads:[~2026-11-08  3:12 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-28  0:52 [PATCH 0/5] drm/vkms: support more formats and fix RGB565 regression Matheus Alves de Almeida
2026-09-28  0:52 ` [PATCH 1/5] drm/vkms: make argb_u16_to_RGB565 round resulting values Matheus Alves de Almeida
2026-11-08  3:12   ` Sidharth Saha [this message]
2026-09-28  0:52 ` [PATCH 2/5] drm/vkms: support BGR565 writeback Matheus Alves de Almeida
2026-09-28  0:52 ` [PATCH 3/5] drm/vkms: add a helper for channel to argb_u16 conversion Matheus Alves de Almeida
2026-09-28  0:53 ` [PATCH 4/5] drm/vkms: add support for RGB332 Matheus Alves de Almeida
2026-09-28  0:53 ` [PATCH 5/5] drm/vkms: add support for BGR233 Matheus Alves de Almeida
2026-10-12 19:18 ` [PATCH 0/5] drm/vkms: support more formats and fix RGB565 regression Matheus Alves de Almeida
2026-11-08  3:08 ` Sidharth Saha
2026-11-13  0:18 ` Sidharth Saha
2026-11-13  1:51   ` Matheus Alves de Almeida

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