From: Mark Brown <broonie@kernel.org> To: Robin Murphy <robin.murphy@arm.com> Cc: Robin Gong <yibin.gong@nxp.com>, "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: Tue, 9 Jun 2020 14:36:27 +0100 [thread overview] Message-ID: <20200609133627.GG4583@sirena.org.uk> (raw) In-Reply-To: <bcfc3637-65af-577a-ddbd-890b6c83a6e6@arm.com> [-- Attachment #1: Type: text/plain, Size: 1363 bytes --] On Tue, Jun 09, 2020 at 11:00:33AM +0100, Robin Murphy wrote: > Ah, I think I understand what's going on now. That's... really ugly :( > Looking at the SPI core code, I think a better way to handle this would be > to have your fallback path call spi_unmap_buf() directly (or perform the > same actions, if exporting that to drivers is unacceptable), then make sure > ->can_dma() returns false after that such that spi_unmap_msg() won't try to > unmap it again. That's a lot more reasonable than trying to fake up a > DMA_TO_DEVICE transfer in the middle of a DMA_FROM_DEVICE operation on the > same buffer. Ideally the driver would be checking in can_dma() if the DMA controller is able to perform transactions rather than letting things run as far as trying to actually do the transfer, that's a whole lot cleaner and more manageable than running into an error doing the transfer. I'm surprised that there's no DMA API way to figure this out TBH. We'll also need some handling for this changing at runtime, we're not expecting this to be dynamic at all - we're expecting it to be a static property of the controller/transfer combination, we didn't contemplate this varying randomly at runtime. Instead of rechecking can_dma() we ought to have a flag saying if we did the mapping (which the bodge Robin suggests above could clear). [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --]
WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org> To: Robin Murphy <robin.murphy@arm.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>, "kernel@pengutronix.de" <kernel@pengutronix.de>, "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>, "martin.fuzzey@flowbird.group" <martin.fuzzey@flowbird.group>, "u.kleine-koenig@pengutronix.de" <u.kleine-koenig@pengutronix.de>, "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>, "shawnguo@kernel.org" <shawnguo@kernel.org>, "dan.j.williams@intel.com" <dan.j.williams@intel.com>, Robin Gong <yibin.gong@nxp.com>, "festevam@gmail.com" <festevam@gmail.com>, "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: Tue, 9 Jun 2020 14:36:27 +0100 [thread overview] Message-ID: <20200609133627.GG4583@sirena.org.uk> (raw) In-Reply-To: <bcfc3637-65af-577a-ddbd-890b6c83a6e6@arm.com> [-- Attachment #1.1: Type: text/plain, Size: 1363 bytes --] On Tue, Jun 09, 2020 at 11:00:33AM +0100, Robin Murphy wrote: > Ah, I think I understand what's going on now. That's... really ugly :( > Looking at the SPI core code, I think a better way to handle this would be > to have your fallback path call spi_unmap_buf() directly (or perform the > same actions, if exporting that to drivers is unacceptable), then make sure > ->can_dma() returns false after that such that spi_unmap_msg() won't try to > unmap it again. That's a lot more reasonable than trying to fake up a > DMA_TO_DEVICE transfer in the middle of a DMA_FROM_DEVICE operation on the > same buffer. Ideally the driver would be checking in can_dma() if the DMA controller is able to perform transactions rather than letting things run as far as trying to actually do the transfer, that's a whole lot cleaner and more manageable than running into an error doing the transfer. I'm surprised that there's no DMA API way to figure this out TBH. We'll also need some handling for this changing at runtime, we're not expecting this to be dynamic at all - we're expecting it to be a static property of the controller/transfer combination, we didn't contemplate this varying randomly at runtime. Instead of rechecking can_dma() we ought to have a flag saying if we did the mapping (which the bodge Robin suggests above could clear). [-- Attachment #1.2: signature.asc --] [-- Type: application/pgp-signature, Size: 488 bytes --] [-- Attachment #2: Type: text/plain, Size: 176 bytes --] _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-06-09 13:36 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 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 [this message] 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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