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 0BBA53909A6 for ; Mon, 3 Aug 2026 18:27:20 +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=1785781642; cv=none; b=FsewRwTQfyWmtiYsXuxSRCjQS/Q4Ct8dSbRXzggpM761d5C8wVX60+O2z2yKCMa3zhdDvw8u31hGUnha4WEQjV8H3ODldwMKCVc03I9AqnAD1AqvK1qBFOax+1XilzOJ7/grWjFdMQGKW2phjXoHXQr+CMqDLUq31suvtetFxkY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785781642; c=relaxed/simple; bh=TnZpGq3cjgwLlHolg97XF1m5y4SzL0o9RwrYzFju86o=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=EL0WddCPL1axdmSye3OJ/4iamXPJpumHYn4dCQJzU+vyYrjvwzJtszh0XQ7wt/3HxSKfju2wI6SvqvXX13dzuj6yh8tVUqPmSxE/cXmmNKYhKhYKld1N24CbgYDlMKDawEp3HyCJZGcscup6lm4tM6bfq3DLFsDor5xYcILHuvY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cLduoOmF; 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="cLduoOmF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58E4E1F000E9; Mon, 3 Aug 2026 18:27:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785781640; bh=YKzOprLtohFv0KEenS/ctnXGc/voAI2HyKTrlPqFKbw=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=cLduoOmFZT2nZSZ43fOtFfyCzHRHf2icb5oOViK8ixd4wRVsj84hJRnLTAA5+LPR9 HbfDLyLRi2qs+bgaBurfF2skC0uWIw0qlA4kZYvE4vSRDA3uQmGeh31ZEdylWfoLfO NJtJQrKvJXac2JITkPs6wl8Ex8Tz27u0ngH38iXhhronlFbIb0i/C0jAKfYSOhlMqI BB2f09q6JWlihw1htD5pl8hB+pHT4fA5bQslwiwx1AEh6CoC7/xbRVzcja0cMpsYVm MNyXsQa/Dmz/oNUtIW5VDctkHXRDpoug4KfcZiYcXKHxmaWbUo2ZIgZRTu3I3pz70U 0+TGZhfCvigOQ== From: sashiko-bot@kernel.org Subject: Re: [PATCH v9 06/22] drm/bridge: synopsys: dw-dp: Add missing mutex cleanups on module removal Reply-To: sashiko-reviews@lists.linux.dev To: "Sebastian Reichel" Cc: dri-devel@lists.freedesktop.org, robh@kernel.org, conor+dt@kernel.org, devicetree@vger.kernel.org In-Reply-To: <20260803-synopsys-dw-dp-improvements-v9-6-2e6e46135312@collabora.com> References: <20260803-synopsys-dw-dp-improvements-v9-0-2e6e46135312@collabora.com> <20260803-synopsys-dw-dp-improvements-v9-6-2e6e46135312@collabora.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 03 Aug 2026 18:27:19 +0000 Message-Id: <20260803182720.58E4E1F000E9@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 3 potential issue(= s) to consider: Pre-existing issues: - [High] Missing Completion Reinitialization causes permanent link training= desynchronization on timeouts. - [High] Concurrent hardware modification between the HPD worker and non-bl= ocking atomic commits leads to hardware state corruption. - [Medium] Hotplug events can be lost due to overwriting the single boolean= tracking variable `dp->hotplug.long_hpd` before the worker processes it. -- --- Patch [6]: [PATCH v9 06/22] drm/bridge: synopsys: dw-dp: Add missing mu= tex cleanups on module removal --- commit d8b2520d774bd92589d70544eca3e846bc879920 Author: Sebastian Reichel drm/bridge: synopsys: dw-dp: Add missing mutex cleanups on module removal The driver is currently missing to fully clean up after itself. Ensure that the mutex is cleaned up. Reported-by: Sashiko > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/br= idge/synopsys/dw-dp.c > index facd1c4799923..af3fa7886429b 100644 > --- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c > +++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c > @@ -2039,9 +2039,12 @@ struct dw_dp *dw_dp_probe(struct platform_device *= pdev, const struct dw_dp_plat_ > dp->pixel_mode =3D plat_data->pixel_mode; > dp->plat_data.max_link_rate =3D plat_data->max_link_rate; > =20 > - mutex_init(&dp->irq_lock); > init_completion(&dp->complete); [Severity: High] This isn't a bug introduced by this patch, but while looking at the completion initialization, I noticed a potential regression. If dw_dp_aux_transfer() times out and returns -ETIMEDOUT, and a delayed hardware reply or spurious IRQ later completes the completion: drivers/gpu/drm/bridge/synopsys/dw-dp.c:dw_dp_aux_transfer() { ... regmap_write(dp->regmap, DW_DP_AUX_CMD, value); status =3D wait_for_completion_timeout(&dp->complete, timeout); ... } Would a subsequent call to dw_dp_aux_transfer() immediately consume the sta= le completion since reinit_completion() is not called before the transfer? Could this lead to garbage DPCD reads and permanent link training failure? > =20 > + ret =3D devm_mutex_init(dev, &dp->irq_lock); > + if (ret) > + return ERR_PTR(ret); > + > res =3D devm_platform_ioremap_resource(pdev, 0); > if (IS_ERR(res)) > return ERR_CAST(res); [Severity: Medium] This is a pre-existing issue, but could hotplug events be lost if a short pulse overwrites the state before the worker processes it? If a monitor is plugged in and asserts a long HPD pulse, and a short HPD pulse occurs before the worker executes: drivers/gpu/drm/bridge/synopsys/dw-dp.c:dw_dp_handle_hpd_event() { ... if (value & HPD_IRQ) { dev_dbg(dp->dev, "IRQ from the HPD\n"); dp->hotplug.long_hpd =3D false; regmap_write(dp->regmap, DW_DP_HPD_STATUS, HPD_IRQ); } ... } Does this overwrite the boolean flag, causing the worker to branch incorrec= tly and skip the hotplug notification? drivers/gpu/drm/bridge/synopsys/dw-dp.c:dw_dp_hpd_work() { ... if (!long_hpd) { if (dw_dp_needs_link_retrain(dp)) { ret =3D dw_dp_link_retrain(dp); ... } [Severity: High] This is a pre-existing issue, but I am wondering if there is a concurrent hardware modification regression between the HPD worker and non-blocking atomic commits. The worker relies on connection_mutex, which DRM does not hold during asynchronous atomic hardware commits: drivers/gpu/drm/bridge/synopsys/dw-dp.c:dw_dp_link_retrain() { ... for (;;) { ret =3D drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx); if (ret !=3D -EDEADLK) break; drm_modeset_backoff(&ctx); } ... } Concurrently, dw_dp_bridge_atomic_enable() executes in the commit worker without connection_mutex: drivers/gpu/drm/bridge/synopsys/dw-dp.c:dw_dp_bridge_atomic_enable() { ... ret =3D dw_dp_link_enable(dp); if (ret < 0) { ... } Could both paths attempt to modify PHY and DPCD registers simultaneously, leading to hardware corruption or link training failures? --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260803-synopsys-d= w-dp-improvements-v9-0-2e6e46135312@collabora.com?part=3D6