On Thu, Sep 19, 2019 at 09:38:04AM +0100, Russell King - ARM Linux admin wrote: > Hi, > > Thanks for the reply. > > I see that this bit is marked "reserved" in the LX2160A reference > manual. Sorry, I was lookin at bit 5, it's actually bit 6. Rest of my mail is still relevent. > > This brings up some further questions. > > The DT property "dma-coherent" is used to tell the OS whether the > device is DMA coherent or not. If this property is missing, but the > device is set as DMA coherent, and the OS uses "normal, non-cacheable" > memory for the ADMA table, then errors can occur if there are stale > cache lines corresponding to the memory used. The eSDHC controller > will see the stale cache lines, but the CPU will not. > > Adding "dma-coherent" to the DT declarations alone does not seem to > be the right solution - if we have an OS that does not set the > ESDHC_DMA_SNOOP bit, then we have a similar issue. > > Shouldn't ESDHC_DMA_SNOOP be set depending on whether the device is > DMA coherent or not? > > Note that the device is _not_ marked as "dma-coherent" in either > mainline nor in the LSDK-19.06-V4.19 branch of > https://source.codeaurora.org/external/qoriq/qoriq-components/linux > to avoid ADMA descriptor fetch errors, which leads to this error that > has now been observed with v5.3 kernels - caused precisely as I > describe above. > > Thanks. > > On Thu, Sep 19, 2019 at 08:15:00AM +0000, Y.b. Lu wrote: > > Hi Russell, > > > > The ESDHC_DMA_SNOOP bit is always set in eSDHC driver for DMA. > > > > 1b - DMA transactions are snooped by the CPU data cache. > > 0b - DMA transactions are not snooped by the CPU data cache. > > > > Thanks a lot. > > > > Best regards, > > Yangbo Lu > > > > > -----Original Message----- > > > From: Russell King - ARM Linux admin <linux@xxxxxxxxxxxxxxx> > > > Sent: Thursday, September 19, 2019 3:05 PM > > > To: Y.b. Lu <yangbo.lu@xxxxxxx> > > > Cc: Leo Li <leoyang.li@xxxxxxx>; Fabio Estevam <festevam@xxxxxxxxx>; > > > Adrian Hunter <adrian.hunter@xxxxxxxxx>; Christoph Hellwig <hch@xxxxxx>; > > > Linux ARM <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; Nicolin Chen > > > <nicoleotsuka@xxxxxxxxx>; Will Deacon <will.deacon@xxxxxxx>; dann > > > frazier <dann.frazier@xxxxxxxxxxxxx>; linux-mmc > > > <linux-mmc@xxxxxxxxxxxxxxx> > > > Subject: Re: [REGRESSION] sdhci no longer detects SD cards on LX2160A > > > > > > Hi, > > > > > > This is not the issue, since the problem has been observed with eMMC too, > > > and is sporadic in nature. > > > > > > Please could you answer the question posed: are the eSDHC controllers DMA > > > coherent or are they not coherent? > > > > > > Thanks. > > > > > > On Thu, Sep 19, 2019 at 04:13:20AM +0000, Y.b. Lu wrote: > > > > Sorry. My email was rejected by mailing lists. Let me re-send. > > > > > > > > Hi Russell, > > > > > > > > I’m not sure what board you were using for LX2160A. > > > > We had an known issue for eSDHC controller and all NXP Layerscape RDB > > > boards. > > > > eSDHC couldn’t provide power-cycle to SD card, and even worse, board > > > reset couldn’t provide power-cycle to SD card either. > > > > But for UHS-I SD card, it’s required to have a power-cycle to reset card if it > > > goes into UHS-I mode. Otherwise, we don’t know what will happen when > > > kernel initializes SD card after a reboot/reset. > > > > > > > > I could reproduce that issue with below steps on latest mainline kernel. > > > > 1. Power off board, and power on board. > > > > 2. Start up kernel, the SD card works fine in UHS-I mode. > > > > 3. Reboot/reset board. (This couldn’t provide power-cycle to SD card) > > > > 4. Start up kernel, the SD card gets that ADMA error issue. > > > > > > > > So could you have a try to power off/power on the board, and then start up > > > kernel. Don’t use reboot, or board reset button. > > > > Or you can remove SD card and start up kernel, and insert SD card when > > > kernel has been started up. > > > > Thanks a lot. > > > > > > > > Best regards, > > > > Yangbo Lu > > > > > > > > > > > > From: Li Yang <leoyang.li@xxxxxxx> > > > > Sent: Wednesday, September 18, 2019 1:48 AM > > > > To: Fabio Estevam <festevam@xxxxxxxxx>; Y.b. Lu <yangbo.lu@xxxxxxx> > > > > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>; Christoph Hellwig > > > > <hch@xxxxxx>; Linux ARM <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; > > > > Nicolin Chen <nicoleotsuka@xxxxxxxxx>; Russell King - ARM Linux admin > > > > <linux@xxxxxxxxxxxxxxx>; Will Deacon <will.deacon@xxxxxxx>; dann > > > > frazier <dann.frazier@xxxxxxxxxxxxx>; linux-mmc > > > > <linux-mmc@xxxxxxxxxxxxxxx> > > > > Subject: Re: [REGRESSION] sdhci no longer detects SD cards on LX2160A > > > > > > > > > > > > > > > > On Tue, Sep 17, 2019 at 6:31 PM Fabio Estevam > > > <mailto:festevam@xxxxxxxxx> wrote: > > > > [Adding Li Yang] > > > > > > > > On Tue, Sep 17, 2019 at 10:52 AM Russell King - ARM Linux admin > > > > <mailto:linux@xxxxxxxxxxxxxxx> wrote: > > > > > > > > > The pressing question seems to be this: > > > > > > > > > > Are the eSDHC on the LX2160A DMA coherent or are they not? > > > > > > > > > > Any chances of finding out internally what the true answer to that, > > > > > rather than me poking about trying stuff experimentally? Having a > > > > > definitive answer for a potentially data-corrupting change would be > > > > > really good... > > > > > > > > Li Yang, > > > > > > > > Could you please help to confirm Russell's question? > > > > Adding Yangbo who is working on SDHC. > > > > > > > > Regards, > > > > Leo > > > > > > -- > > > RMK's Patch system: > > > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ar > > > mlinux.org.uk%2Fdeveloper%2Fpatches%2F&data=02%7C01%7Cyangbo.l > > > u%40nxp.com%7C7eca2b9652104c95a52008d73ccfa99a%7C686ea1d3bc2b4 > > > c6fa92cd99c5c301635%7C0%7C0%7C637044734911465102&sdata=QB > > > SEzA9L2HC99gm65P965E3o%2FhNM18u2SouOZxTEs6s%3D&reserved=0 > > > FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps > > > up According to speedtest.net: 11.9Mbps down 500kbps up > > -- > RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up > According to speedtest.net: 11.9Mbps down 500kbps up > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
