From: Mark Brown <broonie@kernel.org>
To: Robin Gong <yibin.gong@nxp.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"vkoul@kernel.org" <vkoul@kernel.org>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"shawnguo@kernel.org" <shawnguo@kernel.org>,
"festevam@gmail.com" <festevam@gmail.com>,
"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
"martin.fuzzey@flowbird.group" <martin.fuzzey@flowbird.group>,
"u.kleine-koenig@pengutronix.de" <u.kleine-koenig@pengutronix.de>,
"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
"matthias.schiffer@ew.tq-group.com"
<matthias.schiffer@ew.tq-group.com>,
"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
dl-linux-imx <linux-imx@nxp.com>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>
Subject: Re: [PATCH v9 RESEND 01/13] spi: imx: add dma_sync_sg_for_device after fallback from dma
Date: Mon, 8 Jun 2020 16:31:39 +0100 [thread overview]
Message-ID: <20200608153139.GI4593@sirena.org.uk> (raw)
In-Reply-To: <VE1PR04MB66388F89015F774EE3FFF69D89850@VE1PR04MB6638.eurprd04.prod.outlook.com>
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On Mon, Jun 08, 2020 at 03:08:45PM +0000, Robin Gong wrote:
> > > + if (transfer->rx_sg.sgl) {
> > > + struct device *rx_dev = spi->controller->dma_rx->device->dev;
> > > +
> > > + dma_sync_sg_for_device(rx_dev, transfer->rx_sg.sgl,
> > > + transfer->rx_sg.nents, DMA_TO_DEVICE);
> > > + }
> > > +
> > This is confusing - why are we DMA mapping to the device after doing a PIO
> > transfer?
> 'transfer->rx_sg.sgl' condition check that's the case fallback PIO after DMA transfer
> failed. But the spi core still think the buffer should be in 'device' while spi driver
> touch it by PIO(CPU), so sync it back to device to ensure all received data flush to DDR.
So we sync it back to the device so that we can then do another sync to
CPU? TBH I'm a bit surprised that there's a requirement that we
explicitly undo a sync and that a redundant double sync in the same
direction might be an issue but I've not had a need to care so I'm
perfectly prepared to believe there is.
At the very least this needs a comment.
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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Robin Gong <yibin.gong@nxp.com>
Cc: "mark.rutland@arm.com" <mark.rutland@arm.com>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"matthias.schiffer@ew.tq-group.com"
<matthias.schiffer@ew.tq-group.com>,
"martin.fuzzey@flowbird.group" <martin.fuzzey@flowbird.group>,
"catalin.marinas@arm.com" <catalin.marinas@arm.com>,
"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
"will.deacon@arm.com" <will.deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
"vkoul@kernel.org" <vkoul@kernel.org>,
"robh+dt@kernel.org" <robh+dt@kernel.org>,
dl-linux-imx <linux-imx@nxp.com>,
"festevam@gmail.com" <festevam@gmail.com>,
"u.kleine-koenig@pengutronix.de" <u.kleine-koenig@pengutronix.de>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
"dan.j.williams@intel.com" <dan.j.williams@intel.com>,
"shawnguo@kernel.org" <shawnguo@kernel.org>,
"kernel@pengutronix.de" <kernel@pengutronix.de>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v9 RESEND 01/13] spi: imx: add dma_sync_sg_for_device after fallback from dma
Date: Mon, 8 Jun 2020 16:31:39 +0100 [thread overview]
Message-ID: <20200608153139.GI4593@sirena.org.uk> (raw)
In-Reply-To: <VE1PR04MB66388F89015F774EE3FFF69D89850@VE1PR04MB6638.eurprd04.prod.outlook.com>
[-- Attachment #1.1: Type: text/plain, Size: 1029 bytes --]
On Mon, Jun 08, 2020 at 03:08:45PM +0000, Robin Gong wrote:
> > > + if (transfer->rx_sg.sgl) {
> > > + struct device *rx_dev = spi->controller->dma_rx->device->dev;
> > > +
> > > + dma_sync_sg_for_device(rx_dev, transfer->rx_sg.sgl,
> > > + transfer->rx_sg.nents, DMA_TO_DEVICE);
> > > + }
> > > +
> > This is confusing - why are we DMA mapping to the device after doing a PIO
> > transfer?
> 'transfer->rx_sg.sgl' condition check that's the case fallback PIO after DMA transfer
> failed. But the spi core still think the buffer should be in 'device' while spi driver
> touch it by PIO(CPU), so sync it back to device to ensure all received data flush to DDR.
So we sync it back to the device so that we can then do another sync to
CPU? TBH I'm a bit surprised that there's a requirement that we
explicitly undo a sync and that a redundant double sync in the same
direction might be an issue but I've not had a need to care so I'm
perfectly prepared to believe there is.
At the very least this needs a comment.
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next prev parent reply other threads:[~2020-06-08 15:31 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-06 23:21 [PATCH v9 RESEND 00/13] add ecspi ERR009165 for i.mx6/7 soc family Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 01/13] spi: imx: add dma_sync_sg_for_device after fallback from dma Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-08 14:34 ` Mark Brown
2020-06-08 14:34 ` Mark Brown
2020-06-08 15:08 ` Robin Gong
2020-06-08 15:08 ` Robin Gong
2020-06-08 15:31 ` Mark Brown [this message]
2020-06-08 15:31 ` Mark Brown
2020-06-08 16:44 ` Robin Murphy
2020-06-08 16:44 ` Robin Murphy
2020-06-09 5:21 ` Robin Gong
2020-06-09 5:21 ` Robin Gong
2020-06-09 10:00 ` Robin Murphy
2020-06-09 10:00 ` Robin Murphy
2020-06-09 10:09 ` (EXT) " Matthias Schiffer
2020-06-09 10:09 ` Matthias Schiffer
2020-06-09 13:26 ` Mark Brown
2020-06-09 13:26 ` Mark Brown
2020-06-09 10:10 ` Robin Gong
2020-06-09 10:10 ` Robin Gong
2020-06-09 13:36 ` Mark Brown
2020-06-09 13:36 ` Mark Brown
2020-06-09 2:45 ` Robin Gong
2020-06-09 2:45 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 02/13] Revert "ARM: dts: imx6q: Use correct SDMA script for SPI5 core" Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 03/13] Revert "ARM: dts: imx6: Use correct SDMA script for SPI cores" Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 04/13] Revert "dmaengine: imx-sdma: refine to load context only once" Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 05/13] dmaengine: imx-sdma: remove duplicated sdma_load_context Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 06/13] dmaengine: imx-sdma: add mcu_2_ecspi script Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 07/13] spi: imx: fix ERR009165 Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 08/13] spi: imx: remove ERR009165 workaround on i.mx6ul Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 09/13] spi: imx: add new i.mx6ul compatible name in binding doc Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 10/13] dmaengine: imx-sdma: remove ERR009165 on i.mx6ul Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 11/13] dma: imx-sdma: add i.mx6ul compatible name Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 12/13] dmaengine: imx-sdma: fix ecspi1 rx dma not work on i.mx8mm Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-06 23:21 ` [PATCH v9 RESEND 13/13] dmaengine: imx-sdma: add uart rom script Robin Gong
2020-06-06 23:21 ` Robin Gong
2020-06-08 9:11 ` (EXT) [PATCH v9 RESEND 00/13] add ecspi ERR009165 for i.mx6/7 soc family Matthias Schiffer
2020-06-08 9:11 ` Matthias Schiffer
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