From: Abel Vesa <abel.vesa@linaro.org>
To: Val Packett <val@packett.cool>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
Suraj Kandpal <suraj.kandpal@intel.com>,
Arun R Murthy <arun.r.murthy@intel.com>,
ankit.k.nautiyal@intel.com, dri-devel@lists.freedesktop.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/dp: drm_edp_backlight_set_level: do not always send 3-byte commands
Date: Thu, 21 Aug 2025 13:17:15 +0300 [thread overview]
Message-ID: <aKbyKwf5XyUbVwdw@linaro.org> (raw)
In-Reply-To: <20250706204446.8918-1-val@packett.cool>
On 25-07-06 17:42:24, Val Packett wrote:
> At least some panels using the LSB register are not happy with the
> unconditional increase of the command buffer to 3 bytes.
>
> With the BOE NE14QDM in my Dell Latitude 7455, the recent patches for
> luminance based brightness have introduced a regression: the brightness
> range stopped being contiguous and became nonsensical (it probably was
> interpreting the last 2 bytes of the buffer and not the first 2).
>
> Change from using a fixed sizeof() to a length variable that's only
> set to 3 when luminance is used. Let's leave the default as 2 even for
> the single-byte version, since that's how it worked before.
>
> Fixes: f2db78e37fe7 ("drm/dp: Modify drm_edp_backlight_set_level")
> Signed-off-by: Val Packett <val@packett.cool>
Tested on Dell XPS 13 9345 which has LGD 134WT1 panel.
Without this, the panel doesn't come up at all on boot.
Tested-by: Abel Vesa <abel.vesa@linaro.org>
next prev parent reply other threads:[~2025-08-21 10:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-06 20:42 [PATCH] drm/dp: drm_edp_backlight_set_level: do not always send 3-byte commands Val Packett
2025-07-07 3:57 ` Kandpal, Suraj
2025-08-21 10:17 ` Abel Vesa [this message]
2025-08-21 10:43 ` Dmitry Baryshkov
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