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bh=cnyTpjFHVwtEUE1dZJKrBGhVFLRLW0sRLYWbADUw1sU=; b=F0ZIv0+8vYhfgo48Uu7lEnCbBqBRRZaAabXVRq4ahaJsEgmhLlYkXSAvyzHmX7Da1uZAqptQ2vXtk+ggRNzS/gJJjLg4CQkQA/dsg3dMrtvYe7BBtMOdLcV+iggC/QyDjThxoAD29klFhvcbTRiq9s9B4ifmn9IBhJWAkRTG9N8= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=leandro.ribeiro@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1785437218; s=zohomail; d=collabora.com; i=leandro.ribeiro@collabora.com; h=Message-ID:Date:Date:MIME-Version:Subject:Subject:To:To:Cc:Cc:From:From:In-Reply-To:Content-Type:Content-Transfer-Encoding:Message-Id:Reply-To; bh=cnyTpjFHVwtEUE1dZJKrBGhVFLRLW0sRLYWbADUw1sU=; b=UXq+3cPCq/Lzc6VinPo8pkRXKfi4huJBl16F4e9tU2t8UG5dAG6O+ozVAa9fHxen T/aQXDt75L3dNCztdALXbSk5ZU7cbpkFWM+c8IWu497F5jyb8vKtbaxlqgZC0ITvbfT 9c4LW9M94BUn0XmkjYwOAcVIlO8U+iC4fCqP6h7w= Received: by mx.zohomail.com with SMTPS id 1785437214954360.024094066045; Thu, 30 Jul 2026 11:46:54 -0700 (PDT) Message-ID: <2167238c-ca2b-443b-ac79-a1975e175509@collabora.com> Date: Thu, 30 Jul 2026 15:46:48 -0300 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] drm: use drm_warn() in validate_blend_mode_for_alpha_formats() To: Jani Nikula , dri-devel@lists.freedesktop.org Cc: airlied@gmail.com, broonie@kernel.org, daniels@collabora.com, maarten.lankhorst@linux.intel.com, miguel.ojeda.sandonis@gmail.com, mripard@kernel.org, pekka.paalanen@collabora.com, simona@ffwll.ch, penguin-kernel@I-love.SAKURA.ne.jp, tytso@mit.edu, tzimmermann@suse.de, ville.syrjala@linux.intel.com, linux-kernel@vger.kernel.org References: <20260729214505.185776-1-leandro.ribeiro@collabora.com> <20260729214505.185776-2-leandro.ribeiro@collabora.com> Content-Language: en-US From: Leandro Ribeiro In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ZohoMailClient: External On 7/30/26 6:14 AM, Jani Nikula wrote: > On Wed, 29 Jul 2026, Leandro Ribeiro wrote: >> Commit 860e748bddcc ("drm: ensure blend mode supported if pixel format >> with alpha exposed") introduced a WARN() to let driver developers know >> that a previously valid behavior should now be changed. > > I should've chimed in way back when, but in retrospect it's a bit > presumptuous to add a commit that puts the burden of the change on the > driver developers, without so much as identifying which drivers or > getting an ack from them. > > This is really not unlike the __deprecated attribute, see commit > 771c035372a0 ("deprecate the '__deprecated' attribute warnings entirely > and for good"), but this one's runtime not build. > I agree. I hadn't considered the driver coordination aspect when proposing that change. >> But WARN() should not be used for that, as it's a kernel warning report >> mechanism for conditions that are not expected to happen. It also >> produces a stack trace. Instead, a simple warning-level log message >> should have been used, as drivers were expected to trigger the >> condition. >> >> This is causing problems for fuzzers, as they may stop when encountering >> a "BUG:" or "WARNING:" in the logs. >> >> Replace WARN() with drm_warn() in this function, avoiding these issues. > > Fixes: 860e748bddcc ("drm: ensure blend mode supported if pixel format with alpha exposed") > >> Signed-off-by: Leandro Ribeiro >> --- >> drivers/gpu/drm/drm_mode_config.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/gpu/drm/drm_mode_config.c b/drivers/gpu/drm/drm_mode_config.c >> index 3bcc7bf0900c..3d9c554e08a8 100644 >> --- a/drivers/gpu/drm/drm_mode_config.c >> +++ b/drivers/gpu/drm/drm_mode_config.c >> @@ -869,8 +869,9 @@ static void validate_blend_mode_for_alpha_formats(struct drm_plane *plane) >> for (i = 0; i < plane->format_count; i++) { >> fmt = drm_format_info(plane->format_types[i]); >> if (fmt->has_alpha) { >> - WARN(1, "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup", >> - plane->base.id, plane->name); >> + drm_warn(plane->dev, >> + "[PLANE:%d:%s] pixel format with alpha exposed but blend mode not setup", >> + plane->base.id, plane->name); >> break; >> } >> } > -- Leandro Ribeiro