From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1ABDC3B2D06 for ; Mon, 15 Jun 2026 06:40:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781505644; cv=none; b=Wk4MjghJ/KD8Q8YU6x6713Vs2q91pejK4iqRoZut+YU8mk6wXrVL9umN+1rPeNvmE+HRKvdTJyui6+WW7knh8CEW2rQkYlWC6CbJtVKi381F+rOweBWCRwla8s9F3mXpRRrTSs0p0Rd7vG8XA+U8wzKbj9j9MMtCPm5QbnWH7GU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781505644; c=relaxed/simple; bh=qlyGeyNmGTzrC54k5kkkSWJw4ZVq3zNqkMH/l0Z8bBA=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=Qm+3zr9hJDsoFZiD36EfMyjY2VDjOhODrgXCeQVq/0acdq9PhkVaa3bH3NU7uNNUNEv/8WtV5VwBmartXNwVyIagScOQ9fSLAfn5pnVfyZM7HF4/fLW6iMkBSVOzux9qhX/fejlu0RdBJF+OPWrZXQ2h13U7rOdBj87qOGShw0Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IY0baVte; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IY0baVte" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7192E1F000E9; Mon, 15 Jun 2026 06:40:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781505642; bh=7yNAmv61JvbQHkwqcWNf6ZNYI3rUcJOTchHFJDRbC1s=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=IY0baVteZOrScnI5uuLiQ+1eE5dWKF24/NSGGToEp4CkkJEOc3bvXHzSaTlIUnrGI Mx2ijSMEB0LFtbMCgjw3P+xhiMq52YB1sYDP/X8zCOkH7+t53u1SV+fwf4L6Ma89pm uV1aXZcsJftvMA8CoU6D5tx6ADtFcFYslCbxUUd8Rd7TWY17Y+6NmaqFKwStoFx1eW Cj3XLNZtT4UbLkX72Mz5F5Xck8Am8Jyhsc7Q/XBm3q5Jg+xrJO92smLB7rtyOlS0Ue AsoEvL5f3ZYaV59xXKFPEhOoYBwjwvtztzR09k7v+EUKrXjQQHeaNJ9whaIiLeydgn KZXAunq95wUfQ== From: sashiko-bot@kernel.org Subject: Re: [PATCH v4 3/7] drm/rcar-du: dsc: Add rudimentary Renesas R-Car V4H DSC driver Reply-To: sashiko-reviews@lists.linux.dev To: "Tomi Valkeinen" Cc: robh@kernel.org, wsa+renesas@sang-engineering.com, conor+dt@kernel.org, devicetree@vger.kernel.org, dri-devel@lists.freedesktop.org In-Reply-To: <20260615-rcar-du-dsc-v4-3-93096a1b56a3@ideasonboard.com> References: <20260615-rcar-du-dsc-v4-3-93096a1b56a3@ideasonboard.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 15 Jun 2026 06:40:42 +0000 Message-Id: <20260615064042.7192E1F000E9@smtp.kernel.org> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 4 potential issue(= s) to consider: - [High] `WARN_ON(pm_runtime_get_sync(dsc->dev))` incorrectly warns on succ= ess and mishandles errors. - [High] Mixing devm-managed bridge registration with manual runtime PM man= ipulation creates race conditions during probe and removal. - [Low] The driver calls `of_drm_get_bridge_by_endpoint()`, which does not = exist anywhere in the kernel, causing a build failure. - [Low] Dead Kconfig dependency prevents `DRM_RCAR_DSC` from ever compiling= under `COMPILE_TEST`. -- commit 6b399ab87555498e65f4bb3171342804aa8feb3a Author: Marek Vasut drm/rcar-du: dsc: Add rudimentary Renesas R-Car V4H DSC driver The Renesas DSC Display Stream Compression is a bridge embedded in the Renesas R-Car V4H SoC. The bridge performs VESA DSC encoding of up to 8k or 400 Mpixel/s. Add rudimentary driver, which currently acts as a pass-through bridge and allows DSI1 to be operational on R-Car V4H. > diff --git a/drivers/gpu/drm/renesas/rcar-du/Kconfig b/drivers/gpu/drm/re= nesas/rcar-du/Kconfig > index 840305fdeb49a..80bd770ae0f68 100644 > --- a/drivers/gpu/drm/renesas/rcar-du/Kconfig > +++ b/drivers/gpu/drm/renesas/rcar-du/Kconfig [ ... ] > @@ -25,6 +25,18 @@ config DRM_RCAR_CMM > def_tristate DRM_RCAR_DU > depends on DRM_RCAR_USE_CMM > =20 > +config DRM_RCAR_USE_DSC > + bool "R-Car DU DSC Encoder Support" > + depends on DRM_BRIDGE && OF > + depends on DRM_RCAR_DU || COMPILE_TEST > + default DRM_RCAR_DU > + help > + Enable support for the R-Car Display Unit embedded DSC encoder. > + > +config DRM_RCAR_DSC > + def_tristate DRM_RCAR_DU > + depends on DRM_RCAR_USE_DSC > + [Severity: Low] Will this Kconfig setup prevent compile testing? Since DRM_RCAR_USE_DSC depends on DRM_RCAR_DU || COMPILE_TEST, it can be enabled when DRM_RCAR_DU=3Dn. However, DRM_RCAR_DSC defaults to def_tristate DRM_RCAR_DU. This means when DRM_RCAR_DU=3Dn during a COMPILE_TEST, DRM_RCAR_DSC will be forced to 'n' and rcar_dsc.c will never actually be compiled. > diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_dsc.c b/drivers/gpu/drm= /renesas/rcar-du/rcar_dsc.c > new file mode 100644 > index 0000000000000..5a2ff31491360 > --- /dev/null > +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_dsc.c [ ... ] > +static void rcar_dsc_atomic_enable(struct drm_bridge *bridge, > + struct drm_atomic_commit *commit) > +{ > + struct rcar_dsc *dsc =3D bridge_to_rcar_dsc(bridge); > + > + WARN_ON(pm_runtime_get_sync(dsc->dev)); > +} [Severity: High] Does this WARN_ON trigger on success? pm_runtime_get_sync() returns 1 when the device is already active (RPM_ACTIVE). By wrapping it directly in WARN_ON(), wouldn't this trigger a false-positive stack trace on every successful modeset? [ ... ] > +static int rcar_dsc_probe(struct platform_device *pdev) > +{ > + struct device *dev =3D &pdev->dev; > + struct rcar_dsc *dsc; > + int ret; [ ... ] > + dsc->bridge.next_bridge =3D of_drm_get_bridge_by_endpoint(dev->of_node, > + 1, 0); [Severity: Low] Does this function exist? Calling of_drm_get_bridge_by_endpoint() causes a build failure because it doesn't exist anywhere in the kernel. Was this intended to be devm_drm_of_get_bridge()? > + if (IS_ERR(dsc->bridge.next_bridge)) > + return PTR_ERR(dsc->bridge.next_bridge); > + > + dsc->bridge.of_node =3D dev->of_node; > + > + ret =3D devm_drm_bridge_add(dev, &dsc->bridge); > + if (ret) > + return ret; > + > + pm_runtime_enable(&pdev->dev); > + > + return 0; > +} > + > +static void rcar_dsc_remove(struct platform_device *pdev) > +{ > + pm_runtime_disable(&pdev->dev); > +} [Severity: High] Can these devres and manual pm_runtime calls race? In rcar_dsc_probe(), devm_drm_bridge_add() exposes the bridge to the DRM subsystem before pm_runtime_enable() is called. On teardown, rcar_dsc_remove() manually calls pm_runtime_disable(), but the devres-managed bridge isn't removed until devres_release_all() runs later. Doesn't this create a window where the bridge is fully accessible via DRM but its PM runtime is disabled, potentially causing hardware access faults during concurrent operations? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260615-rcar-du-ds= c-v4-0-93096a1b56a3@ideasonboard.com?part=3D3