> -----Original Message----- > From: Ulf Hansson <ulf.hansson@xxxxxxxxxx> > Sent: Monday, September 23, 2019 4:27 PM > To: Russell King <rmk+kernel@xxxxxxxxxxxxxxx> > Cc: Robin Murphy <robin.murphy@xxxxxxx>; dann frazier > <dann.frazier@xxxxxxxxxxxxx>; Will Deacon <will.deacon@xxxxxxx>; > Nicolin Chen <nicoleotsuka@xxxxxxxxx>; Y.b. Lu <yangbo.lu@xxxxxxx>; > Christoph Hellwig <hch@xxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; > DTML <devicetree@xxxxxxxxxxxxxxx>; Leo Li <leoyang.li@xxxxxxx>; Rob > Herring <robh+dt@xxxxxxxxxx>; Shawn Guo <shawnguo@xxxxxxxxxx>; Linux > ARM <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx> > Subject: Re: [PATCH 3/3] arm64: dts: mark lx2160a esdhc controllers dma > coherent > > On Sun, 22 Sep 2019 at 12:29, Russell King <rmk+kernel@xxxxxxxxxxxxxxx> > wrote: > > > > The LX2160A esdhc controllers are setup by the driver to be DMA > > coherent, but without marking them as such in DT, Linux thinks they > > are not. This can lead to random sporadic DMA errors, even to the > > extent of preventing boot, such as: > > > > mmc0: ADMA error > > mmc0: sdhci: ============ SDHCI REGISTER DUMP =========== > > mmc0: sdhci: Sys addr: 0x00000000 | Version: 0x00002202 > > mmc0: sdhci: Blk size: 0x00000008 | Blk cnt: 0x00000001 > > mmc0: sdhci: Argument: 0x00000000 | Trn mode: 0x00000013 > > mmc0: sdhci: Present: 0x01f50008 | Host ctl: 0x00000038 > > mmc0: sdhci: Power: 0x00000003 | Blk gap: 0x00000000 > > mmc0: sdhci: Wake-up: 0x00000000 | Clock: 0x000040d8 > > mmc0: sdhci: Timeout: 0x00000003 | Int stat: 0x00000001 > > mmc0: sdhci: Int enab: 0x037f108f | Sig enab: 0x037f108b > > mmc0: sdhci: ACmd stat: 0x00000000 | Slot int: 0x00002202 > > mmc0: sdhci: Caps: 0x35fa0000 | Caps_1: 0x0000af00 > > mmc0: sdhci: Cmd: 0x0000333a | Max curr: 0x00000000 > > mmc0: sdhci: Resp[0]: 0x00000920 | Resp[1]: 0x001d8a33 > > mmc0: sdhci: Resp[2]: 0x325b5900 | Resp[3]: 0x3f400e00 > > mmc0: sdhci: Host ctl2: 0x00000000 > > mmc0: sdhci: ADMA Err: 0x00000009 | ADMA Ptr: 0x000000236d43820c > > mmc0: sdhci: ============================================ > > mmc0: error -5 whilst initialising SD card > > > > These are caused by the device's descriptor fetch hitting > > speculatively loaded CPU cache lines that the CPU does not see through > > the normal, non-cacheable DMA coherent mapping that it uses for > > non-coherent devices. > > > > DT and the device must agree wrt whether the device is DMA coherent or > > not. > > > > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx> > > As I am picking up patch1 and patch2 from this series, I can also help out and > pick up this one, if that is okay by people? There is some concern recently from linux-next maintainer about this causing potential conflicts. https://lkml.org/lkml/2019/9/15/225 Regards, Leo
