From: Peter Ujfalusi <peter.ujfalusi@ti.com> To: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Cc: Viresh Kumar <viresh.kumar@linaro.org>, <vireshk@kernel.org>, <axboe@kernel.dk>, <vkoul@kernel.org>, <linux-ide@vger.kernel.org>, <linux-kernel@vger.kernel.org> Subject: Re: [PATCH] ata: pata_arasam_cf: Use dma_request_chan() instead dma_request_slave_channel() Date: Mon, 13 Jan 2020 16:33:01 +0200 Message-ID: <7cb96956-806e-4120-692c-dfd0afd49738@ti.com> (raw) In-Reply-To: <b171c3c0-d924-e2e6-0c4d-196c7e6c2325@samsung.com> On 13/01/2020 13.31, Bartlomiej Zolnierkiewicz wrote: > > On 12/17/19 12:19 PM, Viresh Kumar wrote: >> On 17-12-19, 12:50, Peter Ujfalusi wrote: >>> dma_request_slave_channel() is a wrapper on top of dma_request_chan() >>> eating up the error code. >>> >>> By using dma_request_chan() directly the driver can support deferred >>> probing against DMA. > > It doesn't seem to be the case as DMA channel is requested at the start > of the data transfer (which happens after the driver has been successfully > probed). True, I have updated the commit message to remove the reference to deferred probing. If the DMA is requested upfront (at probe time, device open time?) the driver would save quite a bit of time by not allocating and freeing the DMA resources repeatedly for each transfer, thus most likely giving a boost to throughput... > PS there is a typo in the patch summary (it should "pata_arasan_cf"). Ah, fixed this as well in v2. Thanks for catching them, - Péter > > Best regards, > -- > Bartlomiej Zolnierkiewicz > Samsung R&D Institute Poland > Samsung Electronics > >>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com> >>> --- >>> drivers/ata/pata_arasan_cf.c | 6 ++++-- >>> 1 file changed, 4 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/ata/pata_arasan_cf.c b/drivers/ata/pata_arasan_cf.c >>> index 135173c8d138..69b555d83f68 100644 >>> --- a/drivers/ata/pata_arasan_cf.c >>> +++ b/drivers/ata/pata_arasan_cf.c >>> @@ -526,9 +526,10 @@ static void data_xfer(struct work_struct *work) >>> >>> /* request dma channels */ >>> /* dma_request_channel may sleep, so calling from process context */ >>> - acdev->dma_chan = dma_request_slave_channel(acdev->host->dev, "data"); >>> - if (!acdev->dma_chan) { >>> + acdev->dma_chan = dma_request_chan(acdev->host->dev, "data"); >>> + if (IS_ERR(acdev->dma_chan)) { >>> dev_err(acdev->host->dev, "Unable to get dma_chan\n"); >>> + acdev->dma_chan = NULL; >>> goto chan_request_fail; >>> } >>> >>> @@ -539,6 +540,7 @@ static void data_xfer(struct work_struct *work) >>> } >>> >>> dma_release_channel(acdev->dma_chan); >>> + acdev->dma_chan = NULL; >>> >>> /* data xferred successfully */ >>> if (!ret) { >> >> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> >> > Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki. Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki
prev parent reply index Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-12-17 10:50 Peter Ujfalusi 2019-12-17 11:19 ` Viresh Kumar 2020-01-13 11:31 ` Bartlomiej Zolnierkiewicz 2020-01-13 14:33 ` Peter Ujfalusi [this message]
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