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 413BD3438B5; Sat, 23 May 2026 05:47:09 +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=1779515231; cv=none; b=MTAwblVlXOYxxtpYPp2/T47mzwvNc4iL4wA2Iu6az6oTCPvpf3cWPhsfsnst59WpT2IRn6VdFmiPoVOU8zxwF8Zty4PHTogbY0g5EFVvSya9Zvz+rp4Ucd1L9RdYnAvloe6GQJ0f+QtL5MibOMfhmgIUCdA5u3SxrbY27CAlMnE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779515231; c=relaxed/simple; bh=MXIY6l97tR55QyeX2VEz2DQUUhL3kSBh9Wd5y+y1ngc=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=gfu2xXdhIFUE5z7jqAK0SQkYBtjIvhIW3VntroloANSlvZdVSgqiXUmLPWSvDHyfncE5W/7wmQ94pDzV+LdKLRKMkETlXGc4oAXv7ZtZHW8GXzfSsBu+eZ2KkM1oLVOIkbB0J2OJvrGHAV8MiaxhL3u5wTx6muFfHSp+rQpZl/4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=qdhn4eD6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="qdhn4eD6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 53A0A1F000E9; Sat, 23 May 2026 05:47:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779515229; bh=y/1aL6buhhJBjhbquNQM//2DOfH+rUk/z6aU7VoDjNY=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=qdhn4eD6W7oUiZepqLS7xPGjcH5WAHMeC++P64B6zffuMgSHDbRhaZTdjymgzKGBa hHX/QCphw1FeCIiAtT9V/qK/cVO/L4ptJRgSoU76Jbg+2BgfOaETIXxEBHp0lBvm5F kyZzCF9tbSD62YyYIkNzCsXZNa4FKwCeoy9/hBQo= Date: Sat, 23 May 2026 07:47:12 +0200 From: "gregkh@linuxfoundation.org" To: Matthias Feser Cc: Moteen Shah , "linux-serial@vger.kernel.org" , "jirislaby@kernel.org" , "linux-kernel@vger.kernel.org" , "k-willis@ti.com" , "msp@baylibre.com" , "andriy.shevchenko@linux.intel.com" Subject: Re: [PATCH v4] serial: 8250_omap: clear rx_running on zero-length DMA completes Message-ID: <2026052316-drown-guidable-0e7f@gregkh> References: <4b8c59fe-c6a1-47cb-ab3b-855b1edddde2@ti.com> Precedence: bulk X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, May 22, 2026 at 12:37:25PM +0000, Matthias Feser wrote: > On AM33xx RX DMA only triggers when the FIFO reaches the > configured threshold (typically 48 bytes). For smaller bursts > no DMA request is issued and the FIFO is drained by RX timeout. > > In this case __dma_rx_do_complete() can legitimately see count == 0. > > The current code exits early in this case and does not clear > dma->rx_running, leaving the DMA state inconsistent. This can > prevent RX DMA from restarting and may cause > omap_8250_rx_dma_flush() to fail, marking DMA as broken. > > Fix this by clearing dma->rx_running once the DMA transfer has > completed or been terminated, even if no data was transferred. > > Signed-off-by: Matthias Feser > Reviewed-by: Moteen Shah > --- > Changes in v4: > - Add blank line before dma->rx_running as suggested Please properly start a new thread, don't have this patch be in reply to another one, the "Re:" in it is a bit odd, don't you think? And what commit id does this fix? Should it be backported to stable kernels? If so, how far back? thanks, greg k-h