Hi, On Fri, 2009-06-05 at 17:34 +0200, Joachim Foerster wrote: > we have a very strange problem with SD-card-over-SPI support using > 2.6.29.4 on our custom PowerPC 405 (Virtex-4 FX FPGA) based board. To > summarize the problem in one sentence: mmc_spi gets a timeout (error > -110) after sending MMC command "CMD10" (CID, card identification?).
The problem seems to be these DMA transfers/methods (?), which are used by mmc_spi, if spi->master->dev.parent->dma_mask is non-NULL in mmc_spi_probe() . We detected the problem in form of kind of "data loss/corruption" in mmc_spi_readbytes() after spi_sync() is called. Data is received correctly by xilinx_spi (and thus by spi_sync())! Background: The CMD10 is the first "bigger" ;-) (16 bytes) block transfer, where mmc_spi waits for the token 0xfe by calling mmc_spi_skip() in the end and later on receives these 16 bytes. But the token seems to be "lost/corrupted" and thus a timeout occurs. For now our dirty workaround is, to remove DMA support by commenting out the "if (spi->master->dev.parent->dma_mask)" block in mmc_spi_probe(). Note, that in the old 2.6.26+arch/ppc this dma_mask is NULL - so DMA code is never activated in mmc_spi_probe()! Conclusion: Either DMA code in mmc_spi has a bug OR dma_*() functions have a bug OR the device tree setup code should not assign a dma_mask to xilinx_spi devices? Any hints? Where do we have to look in case there is something wrong in device tree setup? Joachim _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
