On Fri, Aug 28, 2020 at 11:26:57AM +0200, Ulf Hansson wrote: > On Fri, 28 Aug 2020 at 06:24, Christoph Hellwig <hch@xxxxxx> wrote: > > > > On Thu, Aug 27, 2020 at 10:11:53PM -0400, Rich Felker wrote: > > > > This change broke SD card support on J2 because MMC_SPI spuriously > > > > depends on HAS_DMA. It looks like it can be fixed just by removing > > > > that dependency from drivers/mmc/host/Kconfig. > > > > > > It can't. mmp_spi_probe fails with ENOMEM, probably due to trying to > > > do some DMA setup thing that's not going to be needed if the > > > underlying SPI device doesn't support/use DMA. > > > > Adding the linux-mmc and linux-spi lists, as that seems pretty odd. > > The mmc_spi driver needs modernizations, so I am not surprised to see > odd things. > > My guess is that in ->probe() we check "if > (spi->master->dev.parent->dma_mask)" - > and runs dma_map*() > operations, which fails and leads to bailing out of ->probe() to > return an error code. > > However, by looking at the code, one get the feeling that the DMA > support is somewhat prepared to be made optional. I guess it has never > been really tested, as the Kconfig option has "depends on HAS_DMA" - > and it's been like that as long as I can remember. It always worked on our "byte-banged" SPI controller, with no DMA controller present, before Christoph's changes in this patch series, and seems to be working now (although I have some other, hopefully unrelated regressions to debug) with #ifdef CONFIG_HAS_DMA around the if (spi->master->dev.parent->dma_mask) block in mmc_spi_probe. That's probably not the right fix though -- why isn't it checking host->dma_dev instead and only attempting DMA setup if dma_dev is non-null? Rich
