On 24.08.20 13:45, Vignesh Raghavendra wrote: > > > On 8/22/20 11:35 PM, Jan Kiszka wrote: >> On 01.06.20 09:04, Vignesh Raghavendra wrote: >>> dma_request_chan_by_mask() can throw EPROBE_DEFER if DMA provider >>> is not yet probed. Currently driver just falls back to using PIO mode >>> (which is less efficient) in this case. Instead return probe deferral >>> error as is so that driver will be re probed once DMA provider is >>> available. >>> >>> Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx> >>> Reviewed-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxxxxx> >>> --- > [...] >>> >>> static const struct spi_nor_controller_ops cqspi_controller_ops = { >>> @@ -1269,8 +1274,11 @@ static int cqspi_setup_flash(struct cqspi_st *cqspi, struct device_node *np) >>> dev_dbg(nor->dev, "using direct mode for %s\n", >>> mtd->name); >>> >>> - if (!cqspi->rx_chan) >>> - cqspi_request_mmap_dma(cqspi); >>> + if (!cqspi->rx_chan) { >>> + ret = cqspi_request_mmap_dma(cqspi); >>> + if (ret == -EPROBE_DEFER) >>> + goto err; >>> + } >>> } >>> } >>> >>> >> >> This seem to break reading the SPI flash on our IOT2050 [1] (didn't test >> the eval board yet). >> >> Without that commit, read happens via PIO, and that works. With the >> commit, the pattern >> >> with open("out.bin", "wb") as out: >> pos = 0 >> while pos < 2: >> with open("/dev/mtd0", "rb") as mtd: >> mtd.seek(pos * 0x10000) >> out.write(mtd.read(0x10000)) >> pos += 1 >> >> gives the wrong result for the second block while > > Interesting... Could you please explain wrong result? Is the data move > around or completely garbage? It looks like some stripes contain data from other parts of the flash or kernel RAM. It's not just garbage, there are readable strings included. > > Does this fail even on AM654 EVM? Could you share full script for me to > test locally? The scripts are complete (python). Just binary-diff the outputs. I'll try on the EVM later. > > What is the flash on the board? Le, could you answer that more precisely than I could? Thanks, Jan > >> >> with open("out2.bin", "wb") as out: >> with open("/dev/mtd0", "rb") as mtd: >> out.write(mtd.read(0x20000)) >> >> (or "mtd_debug read") is fine. >> >> What could be the reason? Our DTBs and k3-am654-base-board.dtb had some >> deviations /wrt the ospi node, but aligning ours to the base board made >> no difference. >> >> Jan >> >> [1] https://github.com/siemens/linux/commits/jan/iot2050 >> -- Siemens AG, Corporate Technology, CT RDA IOT SES-DE Corporate Competence Center Embedded Linux