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From: Jon Hunter <jonathanh@nvidia.com>
To: "Dmitry Osipenko" <digetx@gmail.com>,
	"Laxman Dewangan" <ldewangan@nvidia.com>,
	"Vinod Koul" <vkoul@kernel.org>,
	"Dan Williams" <dan.j.williams@intel.com>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: <dmaengine@vger.kernel.org>, <linux-tegra@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7 13/19] dmaengine: tegra-apb: Don't stop cyclic DMA in a case of error condition
Date: Tue, 4 Feb 2020 12:02:36 +0000
Message-ID: <332e8e86-dca5-19f2-9ef1-6d89a55f3651@nvidia.com> (raw)
In-Reply-To: <20200202222854.18409-14-digetx@gmail.com>


On 02/02/2020 22:28, Dmitry Osipenko wrote:
> There is no harm in keeping DMA active in the case of error condition,
> which should never happen in practice anyways. This will become useful
> for the next patch, which will keep RPM enabled only during of DMA
> transfer, and thus, it will be much nicer if cyclic DMA handler could
> not touch the DMA-enable state.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/dma/tegra20-apb-dma.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> index c7dc27ef1856..50abce608318 100644
> --- a/drivers/dma/tegra20-apb-dma.c
> +++ b/drivers/dma/tegra20-apb-dma.c
> @@ -571,9 +571,7 @@ static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
>  	 */
>  	hsgreq = list_first_entry(&tdc->pending_sg_req, typeof(*hsgreq), node);
>  	if (!hsgreq->configured) {
> -		tegra_dma_stop(tdc);
> -		dev_err(tdc2dev(tdc), "Error in DMA transfer, aborting DMA\n");
> -		tegra_dma_abort_all(tdc);
> +		dev_err_ratelimited(tdc2dev(tdc), "Error in DMA transfer\n");

While we are at it, a more descriptive error message could be good here.
I believe that this condition would indicate a potential underrun condition.

>  		return false;
>  	}
>  
> @@ -772,7 +770,10 @@ static int tegra_dma_terminate_all(struct dma_chan *dc)
>  	if (!list_empty(&tdc->pending_sg_req) && was_busy) {
>  		sgreq = list_first_entry(&tdc->pending_sg_req, typeof(*sgreq),
>  					 node);
> -		sgreq->dma_desc->bytes_transferred +=
> +		dma_desc = sgreq->dma_desc;
> +
> +		if (dma_desc->dma_status != DMA_ERROR)
> +			dma_desc->bytes_transferred +=
>  				get_current_xferred_count(tdc, sgreq, wcount);

I am wondering if we need to check this here? I assume that the transfer
count would still reflect the amount of data transferred, even if some
was dropped. We will never know how much data was lost.

Jon

-- 
nvpublic

  reply index

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-02 22:28 [PATCH v7 00/19] NVIDIA Tegra APB DMA driver fixes and improvements Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 01/19] dmaengine: tegra-apb: Fix use-after-free Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 02/19] dmaengine: tegra-apb: Prevent race conditions of tasklet vs free list Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 03/19] dmaengine: tegra-apb: Implement synchronization hook Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 04/19] dmaengine: tegra-apb: Prevent race conditions on channel's freeing Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 05/19] dmaengine: tegra-apb: Clean up tasklet releasing Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 06/19] dmaengine: tegra-apb: Use devm_platform_ioremap_resource Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 07/19] dmaengine: tegra-apb: Use devm_request_irq Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 08/19] dmaengine: tegra-apb: Fix coding style problems Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 09/19] dmaengine: tegra-apb: Remove unneeded initialization of tdc->config_init Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 10/19] dmaengine: tegra-apb: Remove assumptions about unavailable runtime PM Dmitry Osipenko
2020-02-04 14:51   ` Jon Hunter
2020-02-02 22:28 ` [PATCH v7 11/19] dmaengine: tegra-apb: Remove pending_sg_req checking from tdc_start_head_req Dmitry Osipenko
2020-02-04 14:53   ` Jon Hunter
2020-02-02 22:28 ` [PATCH v7 12/19] dmaengine: tegra-apb: Remove handling of unrealistic error condition Dmitry Osipenko
2020-02-04 11:52   ` Jon Hunter
2020-02-04 22:17     ` Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 13/19] dmaengine: tegra-apb: Don't stop cyclic DMA in a case of " Dmitry Osipenko
2020-02-04 12:02   ` Jon Hunter [this message]
2020-02-04 15:55     ` Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 14/19] dmaengine: tegra-apb: Keep clock enabled only during of DMA transfer Dmitry Osipenko
2020-02-06 13:50   ` Jon Hunter
2020-02-06 14:31     ` Dmitry Osipenko
2020-02-06 14:33       ` Jon Hunter
2020-02-02 22:28 ` [PATCH v7 15/19] dmaengine: tegra-apb: Clean up suspend-resume Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 16/19] dmaengine: tegra-apb: Add missing of_dma_controller_free Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 17/19] dmaengine: tegra-apb: Allow to compile as a loadable kernel module Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 18/19] dmaengine: tegra-apb: Remove MODULE_ALIAS Dmitry Osipenko
2020-02-02 22:28 ` [PATCH v7 19/19] dmaengine: tegra-apb: Support COMPILE_TEST Dmitry Osipenko

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