On 23/01/14 15:21, Ulf Hansson wrote: > On 23 January 2014 11:09, Adrian Hunter <adrian.hun...@intel.com> wrote: >> On 22/01/14 17:00, Ulf Hansson wrote: >>> Hosts supporting MMC_CAP_WAIT_WHILE_BUSY shall not be waiting for busy >>> detection completion in the recovery path, which were the case when >>> using R1B response. >>> >>> Start using R1 as response instead to align behavior, no matter if >>> MMC_CAP_WAIT_WHILE_BUSY is supported or not. >> >> This does not make sense to me. If you are sending a STOP command you >> should use the correct response type. R1B should be OK here because the >> card should release the busy signal in any case except failure. > > For those hosts not supporting MMC_CAP_WAIT_WHILE_BUSY a R1B is > assumed to be treated same as an R1, which means there are no busy > detection handled in the host.
That is not entirely true. For hosts that do not set MMC_CAP_WAIT_WHILE_BUSY we don't know if they wait or not. I imagine most do because it is more efficient, but the kernel has always been programmed to poll the status anyway so you can't tell from the code. MMC_CAP_WAIT_WHILE_BUSY was one of my inventions I am afraid. If I recall correctly it was mainly due to the SLEEP command because you can't poll in that case and you don't want to delay the system from sleeping - if you are certain that the controller has waited for busy to de-assert (i.e. MMC_CAP_WAIT_WHILE_BUSY) then you can exit immediately. > > mmc_blk_cmd_recovery() is the only caller of the send_stop() function. > Additionally it does not care about to handle busy detection with > CDM13 polling. > > Now, since most hosts don't support MMC_CAP_WAIT_WHILE_BUSY which > means there no busy detection done, I wanted to align to this > behaviour - no matter if the host can do HW busy detection or not. > > I am not saying this is how it must be done, just trying to provide > you with some more reasons to why I wanted to change. > > If we instead decide keep the R1B for send_stop(), we should implement > CMD 13 polling to meet the same behaviour for hosts not supporting > MMC_CAP_WAIT_WHILE_BUSY. In this scenario, we need to set a select a > busy timeout, do you have any suggestion of what would be a reasonable > value for it? It is hard to tell if waiting is ever going to help more than hinder, so I would not change this. > > Kind regards > Ulf Hansson > >> >>> >>> Signed-off-by: Ulf Hansson <ulf.hans...@linaro.org> >>> --- >>> drivers/mmc/card/block.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c >>> index 87cd2b0..74169fa 100644 >>> --- a/drivers/mmc/card/block.c >>> +++ b/drivers/mmc/card/block.c >>> @@ -728,7 +728,7 @@ static int send_stop(struct mmc_card *card, u32 *status) >>> int err; >>> >>> cmd.opcode = MMC_STOP_TRANSMISSION; >>> - cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC; >>> + cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC; >>> err = mmc_wait_for_cmd(card->host, &cmd, 5); >>> if (err == 0) >>> *status = cmd.resp[0]; >>> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
