On Fri, Apr 14, 2017 at 12:41 AM, Bough Chen <haibo.chen@xxxxxxx> wrote: >> -----Original Message----- >> From: Tim Harvey [mailto:tharvey@xxxxxxxxxxxxx] >> Sent: Tuesday, April 11, 2017 10:22 PM >> To: Bough Chen <haibo.chen@xxxxxxx> >> Cc: David Haworth <dave@xxxxxxxxxx>; Linux MMC List <linux- >> mmc@xxxxxxxxxxxxxxx>; Fabio Estevam <fabio.estevam@xxxxxxx>; Ulf >> Hansson <ulf.hansson@xxxxxxxxxx>; Weijun Yang <york.yang@xxxxxxx>; Adrian >> Hunter <adrian.hunter@xxxxxxxxx> >> Subject: Re: IMX6 ESDHC mmc with UHS-I occasional failure with DDR50 cards >> >> On Tue, Apr 11, 2017 at 2:28 AM, Bough Chen <haibo.chen@xxxxxxx> wrote: >> >> -----Original Message----- >> <snip> >> >> >> >> I've moved on to 4.11-rc5 and notice that I'm always seeing that on a >> >> failure the imx sdhc not able to determine a min/max tuning delay: >> >> >> >> 4.11.0-rc5: >> >> [ 48.812381] mmc0: card aaaa removed >> >> [ 49.793392] mmc0: host does not support reading read-only switch, >> >> assuming write-enable >> >> [ 49.810294] sdhci_execute_tuning >> >> [ 49.813612] esdhc_executing_tuning >> >> [ 49.968154] sdhci-esdhc-imx 2198000.usdhc: tuning failed at 0x7f >> >> ret -5 (min=127/max=128) >> >> ^^^^ added debug shows -EIO returned from mmc_send_tuning although >> >> I've also seen -84 get returned >> >> [ 49.980540] mmc0: tuning execution failed: -5 >> >> [ 49.984974] mmc0: ddr50 tuning failed >> >> [ 49.989068] mmc0: new ultra high speed DDR50 SDHC card at address aaaa >> >> [ 49.999844] mmcblk0: mmc0:aaaa SL08G 7.40 GiB >> >> >> >> I've also found that if I revert '9faac7b mmc: sdhci: enable tuning for DDR50' >> >> thus skipping the tuning the issue goes away however note that >> >> occasionally I do see a transfer error that perhaps is retried [ >> >> 361.067763] mmc0: card aaaa removed [ 361.412732] mmc0: host does >> >> not support reading read-only switch, assuming write-enable [ >> >> 361.429719] mmc0: new ultra high speed DDR50 SDHC card at address >> >> aaaa [ 361.443060] mmcblk0: mmc0:aaaa SL08G 7.40 GiB [ 361.465658] >> >> mmcblk0: p1 [ 362.422335] mmc0: card aaaa removed [ 362.752719] >> >> mmc0: host does not support reading read-only switch, assuming >> >> write-enable [ 362.769675] mmc0: new ultra high speed DDR50 SDHC >> >> card at address aaaa [ 362.782900] mmcblk0: mmc0:aaaa SL08G 7.40 GiB >> >> [ 362.805996] >> >> mmcblk0: error -84 transferring data, sector 0, nr 8, cmd response >> >> 0x900, card status 0xb00 ^^^^ occasionally see this error but because >> >> retries occur at the block level it still works [ 362.931689] >> >> mmcblk0: p1 >> >> >> >> Again with 9faac7b reverted and some extra debugging: >> >> [ 33.823170] mmc0: host does not support reading read-only switch, >> >> assuming write-enable >> >> [ 33.847185] mmc0: new ultra high speed DDR50 SDHC card at address aaaa >> >> [ 33.856063] mmcblk0: mmc0:aaaa SL08G 7.40 GiB >> >> [ 33.874227] mmcblk0: error -84 transferring data, sector 0, nr 8, >> >> cmd response 0x900, card status 0xb00 >> >> [ 33.896829] mmcblk0: error -84 transferring data, sector 0, nr 8, >> >> cmd response 0x900, card status 0xb00 >> >> [ 33.906312] mmcblk0: error -84 transferring data, sector 0, nr 8, >> >> cmd response 0x900, card status 0xb00 >> >> [ 34.022117] mmcblk0: error 0 transferring data, sector 0, nr 8, cmd >> >> response 0x900, card status 0xb00 >> >> ^^^^ added debugging shows retries at block level and eventually all is fine >> >> [ 34.031500] mmcblk0: p1 >> >> >> >> So far every DDR50 card I have (several Kingston and Sandisk card >> >> models) behaves like this. >> >> >> >> I tried adding a settling delay when VSELECT was changed in the >> >> sdhci-esdhc- imx driver and that didn't help. >> >> >> > Hi Tim >> > >> > Which imx6 soc do you use? From your log, I notice you use the MAN tuning >> method, so I guess you use imx6qdl. >> > >> > imx usdhc has an IC bug. For the tuning procedure, the first pass tuning delay >> value must bigger than 10. >> > Due to DDR50 timing is not that rigorous, so maybe even when we just add 1 >> delay cell, tuning can pass, but this trigger the internal IC bug, then you meet >> the following issue just as you meet: >> > sdhci-esdhc-imx 2198000.usdhc: tuning failed at 0x7f >> ( min=127/max=128) >> > >> >> Haibo, >> >> Thanks for the response. >> >> Yes, this issue is seen on the IMX6DQ and IMX6SDL. Can you point me to >> information on this bug? I don't see it in the latest IMX6DQCE.pdf errata >> document. >> >> > So you can change the ESDHC_TUNE_CTRL_MIN from 0 to 15, then you can >> see the DDR50 tuning return to normal. >> > >> > For the STD tuning method, you can add the property 'fsl,tuning-start-tap = >> <20>' in dts. >> > >> > All this make the first trying tuning delay value larger than 10, to avoid the >> internal IMX USDHC IC bug. >> > >> > SDR104 card do not has this issue, because for SDR104 card, the first pass >> tuning value normally larger than 10. >> > >> >> unfortunately, this does not resolve the issue. I tried ESDHC_TUNE_CTRL_MIN >> of 15, 20, and 30 and they all produce the same issue around 20% of insertions: >> sdhci-esdhc-imx 2198000.usdhc: tunning failed at 0x7f ret -84 >> >> Here are some min/max tuning values from some various cards I have: >> - Samsung SL08G DDR50: min=8 max=37 >> - Kingston SD8GB DDR50: min=8 max=36 >> - Sandisk SS16G DDR50: min=10 max=37 >> - Sandisk SU08G DDR50: min=9 max=36 >> - Samsung Pro 00000 SDR104: min=14 max=26 >> - Kingston SDR104 SDCIT: min=25 max=36 >> >> All of the DDR50 cards above fail in the same way appx 20% of insertions. >> >> Has anyone else been able to confirm they see the same issue on IMX6 boards >> with UHS-I support and DDR50? > > Hi Tim, > > I debug this issue these days, and find this is the I/O timing issue. > > Can you try to improve the pad I/O drive strength for DDR50 card? You can apply the following patch: > > diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c > index 6a1328e..4c3aeac 100644 > --- a/drivers/mmc/host/sdhci-esdhc-imx.c > +++ b/drivers/mmc/host/sdhci-esdhc-imx.c > @@ -848,6 +848,7 @@ static int esdhc_change_pinstate(struct sdhci_host *host, > > switch (uhs) { > case MMC_TIMING_UHS_SDR50: > + case MMC_TIMING_UHS_DDR50: > pinctrl = imx_data->pins_100mhz; > break; > case MMC_TIMING_UHS_SDR104: > > If this patch also test pass on your side, I will upstream it. > Haibo, Yes, this does resolve the issue where DDR50 cards fail to tune 20% of the time. Using the 100mhz pinctrl's for DDR50 passes tuning every time with a min=1 and max=29 (as opposed to a min=8 max=36 I was seeing on previous successes). Please submit a patch if you don't mind. Also, stable@xxxxxxxxxxxxxxx should be cc'd on the patch and the patch should be applied all the way back to Linux v4.4 where DDR50 tuning first appeared with 9faac7b mmc: sdhci: enable tuning for DDR50. > By the way, I just confirm with our IC guys, the IC bug I mentioned in the before mail do not impact the software tuning method (MAN_TUNING), this IC bug just impact the STD_TUNING, sorry for the mislead. > Ok, thanks for the info. Note still that I don't see anything in the IMX6 errata regarding thisb. Regards, Tim -- 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
