| Message ID | 1629285415-7495-4-git-send-email-haibo.chen@nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2,1/6] mmc: sdhci-esdhc-imx: remove redundant code for manual tuning | expand |
Thank you Haibo for pointing me here from https://www.spinics.net/lists/linux-mmc/msg73270.html. On 2021-08-18 07:16, haibo.chen@nxp.com wrote: > Add a method to enable/disable auto-tuning function. auto-tuning function > is conflict with sdio interrupt. For sdio device with sdio interrupt, > need to disable auto-tuning function. I tested this patch on an imx8mm system and it made things completely unstable. I was never really able to log into the system properly and just got lots of messages similar to the following: [ 31.946640] rcu: INFO: rcu_preempt self-detected stall on CPU [ 31.952422] rcu: 0-....: (2106 ticks this GP) idle=849/1/0x4000000000000000 softirq=902/904 fqs=743 [ 31.961663] (t=2100 jiffies g=33 q=1158) [ 31.965682] Task dump for CPU 0: [ 31.968915] task:kworker/0:1 state:R running task stack: 0 pid: 33 ppid: 2 flags:0x0000000a [ 31.978859] Workqueue: 0x0 (pm) While working on this I also came across https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/uSDHC-auto-tuning-and-possible-SDIO-failures/ta-p/1352855 which seems to address the same issue as your proposed patch. That article suggests only enabling auto tuning for one data line as a workaround. I tried this method and so far it seems to have addressed the -84 errors I was seeing with SDIO communication to a WiFi module. Some thoughts / questions: Why does this proposed patch make my system unstable? (I was testing with a v5.16 mainline based kernel, but I did not see anything in later versions of sdhci-esdhc-imx that seemed like this should be a problem.) Why does this patch try to disable auto tune entirely vs just setting it up for one data bit as suggested in the NXP knowledge base article? As some other have suggested it seems like it would be nicer if the workaround could be applied automatically if the device using the SDIO interface enabled IRQs. Having to include a non standard entry in the DT for a hardware bug you may not know about or understand seems error prone. I guess maybe some device could generate an IRQ before they actually enable IRQs? In that case maybe a DT entry is required, but maybe the driver could generate a warning if IRQs are enabled without the DT entry? Thanks, Kevin
> -----Original Message----- > From: Kevin Groeneveld <kgroeneveld@lenbrook.com> > Sent: 2022年12月5日 23:00 > To: Bough Chen <haibo.chen@nxp.com>; adrian.hunter@intel.com; > ulf.hansson@linaro.org; shawnguo@kernel.org; robh+dt@kernel.org; > s.hauer@pengutronix.de > Cc: kernel@pengutronix.de; festevam@gmail.com; linux-mmc@vger.kernel.org; > dl-linux-imx <linux-imx@nxp.com>; devicetree@vger.kernel.org; > linux-arm-kernel@lists.infradead.org > Subject: Re: [PATCH v2 4/6] mmc: host: sdhci-esdhc-imx.c: disable auto-tuning > when necessary > > Thank you Haibo for pointing me here from > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.spi > nics.net%2Flists%2Flinux-mmc%2Fmsg73270.html&data=05%7C01%7Chai > bo.chen%40nxp.com%7C2c5b5f4d53d04051475308dad6d16673%7C686ea1d3b > c2b4c6fa92cd99c5c301635%7C0%7C0%7C638058492114803922%7CUnknown > %7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwi > LCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=sCV8u6Gv7x%2Bqi6kYSvZ > uZUZeQQ1TaKPwhKpizt49qps%3D&reserved=0. > > On 2021-08-18 07:16, haibo.chen@nxp.com wrote: > > Add a method to enable/disable auto-tuning function. auto-tuning > > function is conflict with sdio interrupt. For sdio device with sdio > > interrupt, need to disable auto-tuning function. > > I tested this patch on an imx8mm system and it made things completely > unstable. I was never really able to log into the system properly and just got lots > of messages similar to the following: > > [ 31.946640] rcu: INFO: rcu_preempt self-detected stall on CPU > [ 31.952422] rcu: 0-....: (2106 ticks this GP) > idle=849/1/0x4000000000000000 softirq=902/904 fqs=743 > [ 31.961663] (t=2100 jiffies g=33 q=1158) > [ 31.965682] Task dump for CPU 0: > [ 31.968915] task:kworker/0:1 state:R running task stack: > 0 pid: 33 ppid: 2 flags:0x0000000a > [ 31.978859] Workqueue: 0x0 (pm) These patch also exist on our local tree, and we do not meet this issue. Can you show me The detail change you added? > > While working on this I also came across > https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcommuni > ty.nxp.com%2Ft5%2Fi-MX-Processors-Knowledge-Base%2FuSDHC-auto-tuning-a > nd-possible-SDIO-failures%2Fta-p%2F1352855&data=05%7C01%7Chaibo.c > hen%40nxp.com%7C2c5b5f4d53d04051475308dad6d16673%7C686ea1d3bc2b > 4c6fa92cd99c5c301635%7C0%7C0%7C638058492114960153%7CUnknown%7C > TWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJX > VCI6Mn0%3D%7C3000%7C%7C%7C&sdata=w3VEjXfQKTIXvIIef1INySnQFU > xW09uafNRdkkv8e7M%3D&reserved=0 > which seems to address the same issue as your proposed patch. > > That article suggests only enabling auto tuning for one data line as a > workaround. I tried this method and so far it seems to have addressed the -84 > errors I was seeing with SDIO communication to a WiFi module. > > Some thoughts / questions: > > Why does this proposed patch make my system unstable? (I was testing with a > v5.16 mainline based kernel, but I did not see anything in later versions of > sdhci-esdhc-imx that seemed like this should be a problem.) > > Why does this patch try to disable auto tune entirely vs just setting it up for one > data bit as suggested in the NXP knowledge base article? > > As some other have suggested it seems like it would be nicer if the workaround > could be applied automatically if the device using the SDIO interface enabled > IRQs. Having to include a non standard entry in the DT for a hardware bug you > may not know about or understand seems error prone. I guess maybe some > device could generate an IRQ before they actually enable IRQs? In that case > maybe a DT entry is required, but maybe the driver could generate a warning if > IRQs are enabled without the DT entry? Yes, your method seems better, I will try to do like that. Thanks Best Regards Haibo Chen > > > Thanks, > Kevin
diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c index f18d169bc8ff..3af6519c561b 100644 --- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c @@ -226,6 +226,7 @@ struct esdhc_platform_data { unsigned int tuning_step; /* The delay cell steps in tuning procedure */ unsigned int tuning_start_tap; /* The start delay cell point in tuning procedure */ unsigned int strobe_dll_delay_target; /* The delay cell for strobe pad (read clock) */ + bool broken_auto_tuning; /* Disable the auto tuning circuit */ }; struct esdhc_soc_data { @@ -672,8 +673,10 @@ static void esdhc_writew_le(struct sdhci_host *host, u16 val, int reg) if (val & SDHCI_CTRL_EXEC_TUNING) { v |= ESDHC_MIX_CTRL_EXE_TUNE; m |= ESDHC_MIX_CTRL_FBCLK_SEL; - m |= ESDHC_MIX_CTRL_AUTO_TUNE_EN; - usdhc_auto_tuning_mode_sel(host); + if (!imx_data->boarddata.broken_auto_tuning) { + usdhc_auto_tuning_mode_sel(host); + m |= ESDHC_MIX_CTRL_AUTO_TUNE_EN; + } } else { v &= ~ESDHC_MIX_CTRL_EXE_TUNE; } @@ -1041,13 +1044,16 @@ static void esdhc_prepare_tuning(struct sdhci_host *host, u32 val) static void esdhc_post_tuning(struct sdhci_host *host) { + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); + struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host); u32 reg; - usdhc_auto_tuning_mode_sel(host); - reg = readl(host->ioaddr + ESDHC_MIX_CTRL); reg &= ~ESDHC_MIX_CTRL_EXE_TUNE; - reg |= ESDHC_MIX_CTRL_AUTO_TUNE_EN; + if (!imx_data->boarddata.broken_auto_tuning) { + usdhc_auto_tuning_mode_sel(host); + reg |= ESDHC_MIX_CTRL_AUTO_TUNE_EN; + } writel(reg, host->ioaddr + ESDHC_MIX_CTRL); } @@ -1522,7 +1528,8 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev, of_property_read_u32(np, "fsl,tuning-step", &boarddata->tuning_step); of_property_read_u32(np, "fsl,tuning-start-tap", &boarddata->tuning_start_tap); - + if (of_property_read_bool(np, "fsl,broken-auto-tuning")) + boarddata->broken_auto_tuning = true; of_property_read_u32(np, "fsl,strobe-dll-delay-target", &boarddata->strobe_dll_delay_target); if (of_find_property(np, "no-1-8-v", NULL))