Hi Adrian, On 12/01/2016 05:15 PM, Adrian Hunter wrote: > On 24/11/16 14:02, Adrian Hunter wrote: >> The JEDEC specification indicates CMD13 can be used after a HS200 switch >> to check for errors. However in practice some boards experience CRC errors >> in the CMD13 response. Consequently, for HS200, CRC errors are not a >> reliable way to know the switch failed. If there really is a problem, we >> would expect tuning will fail and the result ends up the same. So change >> the error condition to ignore CRC errors in that case. >> >> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx> > > Any comments on this? I agreed your opinion..CMD13 can't know whether switch is failed or not with CRC error. It might just know whether HS200 is working fine or not with CRC error. If CRC error is occurred, then user can knows when transfer some data. Then i think it's more easier to debug than now..does it make sense? Acked-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx> Best Regards, Jaehoon Chung > > >> --- >> drivers/mmc/core/mmc.c | 15 ++++++++++++++- >> 1 file changed, 14 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c >> index 3268fcd3378d..34d30e2a09ff 100644 >> --- a/drivers/mmc/core/mmc.c >> +++ b/drivers/mmc/core/mmc.c >> @@ -1223,7 +1223,12 @@ int mmc_hs400_to_hs200(struct mmc_card *card) >> mmc_set_timing(host, MMC_TIMING_MMC_HS200); >> >> err = mmc_switch_status(card); >> - if (err) >> + /* >> + * For HS200, CRC errors are not a reliable way to know the switch >> + * failed. If there really is a problem, we would expect tuning will >> + * fail and the result ends up the same. >> + */ >> + if (err && err != -EILSEQ) >> goto out_err; >> >> mmc_set_bus_speed(card); >> @@ -1387,6 +1392,14 @@ static int mmc_select_hs200(struct mmc_card *card) >> >> err = mmc_switch_status(card); >> /* >> + * For HS200, CRC errors are not a reliable way to know the >> + * switch failed. If there really is a problem, we would expect >> + * tuning will fail and the result ends up the same. >> + */ >> + if (err == -EILSEQ) >> + err = 0; >> + >> + /* >> * mmc_select_timing() assumes timing has not changed if >> * it is a switch error. >> */ >> > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
