From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 DB6601BEF77; Wed, 19 Feb 2025 09:03:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739955840; cv=none; b=LgLiv7UtVLYXIs4XXmB6CfS7/qtuP9U8b5Rr9TgZwnjNBgGMjVJMNe6L1hWaKiqJp4tEgppXa1M2sC+IelJnoPDA7rcmJVN5WrdWOllBUeE4bQkVhLQIblaSl1KUD2tEkB+UPL4a8PqnD8trLSeOuFgrbnSTjC2OOKlzIZcras4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739955840; c=relaxed/simple; bh=KnsDV+bj75YZKyzgWVS4AX5UHboDRkhxNwakLHJkVlg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=CNpv6Os4hyVDs+vAMD7SyRBTnL2uVT8TPEd/9qnk9RxB5FuftfsmYYYLo+j3FCOxEF8YH8QLfPiOjetHxML9jMv+mVD4l6Q1xAoLCJSM7gMl6da793/LT5FOTMfDExndJSImBpCkNuAIVSQgZE+Ilga/LE0BrKWWJdYWec70QNE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mBp12ZbH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="mBp12ZbH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E906CC4CED1; Wed, 19 Feb 2025 09:03:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1739955839; bh=KnsDV+bj75YZKyzgWVS4AX5UHboDRkhxNwakLHJkVlg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mBp12ZbH6Si1qBvsxG9YEOEFeVUvABMNvIWUAoSEeCcLM0MS8cHCrzltg40ODS36e v4tGNh9/92yLLQRYn2HC+bT8MN3FudcvfoGVBXCni8ntm6ZiGIjF62MCo/7u9HVZad O07sAGtuTKPIUwxxddInOnfm9FsW9NXEYXg9OCLM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Bin Liu , Devarsh Thakkar , Jonathan Cormier , Aradhya Bhatia , Tomi Valkeinen Subject: [PATCH 6.6 129/152] drm/tidss: Fix issue in irq handling causing irq-flood issue Date: Wed, 19 Feb 2025 09:29:02 +0100 Message-ID: <20250219082555.153774188@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250219082550.014812078@linuxfoundation.org> References: <20250219082550.014812078@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tomi Valkeinen commit 44b6730ab53ef04944fbaf6da0e77397531517b7 upstream. It has been observed that sometimes DSS will trigger an interrupt and the top level interrupt (DISPC_IRQSTATUS) is not zero, but the VP and VID level interrupt-statuses are zero. As the top level irqstatus is supposed to tell whether we have VP/VID interrupts, the thinking of the driver authors was that this particular case could never happen. Thus the driver only clears the DISPC_IRQSTATUS bits which has corresponding interrupts in VP/VID status. So when this issue happens, the driver will not clear DISPC_IRQSTATUS, and we get an interrupt flood. It is unclear why the issue happens. It could be a race issue in the driver, but no such race has been found. It could also be an issue with the HW. However a similar case can be easily triggered by manually writing to DISPC_IRQSTATUS_RAW. This will forcibly set a bit in the DISPC_IRQSTATUS and trigger an interrupt, and as the driver never clears the bit, we get an interrupt flood. To fix the issue, always clear DISPC_IRQSTATUS. The concern with this solution is that if the top level irqstatus is the one that triggers the interrupt, always clearing DISPC_IRQSTATUS might leave some interrupts unhandled if VP/VID interrupt statuses have bits set. However, testing shows that if any of the irqstatuses is set (i.e. even if DISPC_IRQSTATUS == 0, but a VID irqstatus has a bit set), we will get an interrupt. Co-developed-by: Bin Liu Signed-off-by: Bin Liu Co-developed-by: Devarsh Thakkar Signed-off-by: Devarsh Thakkar Co-developed-by: Jonathan Cormier Signed-off-by: Jonathan Cormier Fixes: 32a1795f57ee ("drm/tidss: New driver for TI Keystone platform Display SubSystem") Cc: stable@vger.kernel.org Tested-by: Jonathan Cormier Reviewed-by: Aradhya Bhatia Signed-off-by: Tomi Valkeinen Link: https://patchwork.freedesktop.org/patch/msgid/20241021-tidss-irq-fix-v1-1-82ddaec94e4a@ideasonboard.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/tidss/tidss_dispc.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) --- a/drivers/gpu/drm/tidss/tidss_dispc.c +++ b/drivers/gpu/drm/tidss/tidss_dispc.c @@ -726,24 +726,20 @@ static void dispc_k3_clear_irqstatus(struct dispc_device *dispc, dispc_irq_t clearmask) { unsigned int i; - u32 top_clear = 0; for (i = 0; i < dispc->feat->num_vps; ++i) { - if (clearmask & DSS_IRQ_VP_MASK(i)) { + if (clearmask & DSS_IRQ_VP_MASK(i)) dispc_k3_vp_write_irqstatus(dispc, i, clearmask); - top_clear |= BIT(i); - } } for (i = 0; i < dispc->feat->num_planes; ++i) { - if (clearmask & DSS_IRQ_PLANE_MASK(i)) { + if (clearmask & DSS_IRQ_PLANE_MASK(i)) dispc_k3_vid_write_irqstatus(dispc, i, clearmask); - top_clear |= BIT(4 + i); - } } if (dispc->feat->subrev == DISPC_K2G) return; - dispc_write(dispc, DISPC_IRQSTATUS, top_clear); + /* always clear the top level irqstatus */ + dispc_write(dispc, DISPC_IRQSTATUS, dispc_read(dispc, DISPC_IRQSTATUS)); /* Flush posted writes */ dispc_read(dispc, DISPC_IRQSTATUS);