RE: [PATCH V2] mmc: sdhci-msm: Reset GCC_SDCC_BCR register for SDHC

Sajida Bhanu (Temp) (QUIC)
2022-03-15T09:17:56Z

Hi,

Thanks for the review.

Please find the inline comments.

Thanks,
Sajida
> -----Original Message-----
> From: Bjorn Andersson <bjorn.andersson@linaro.org>
> Sent: Friday, March 11, 2022 5:10 AM
> To: Sajida Bhanu (Temp) (QUIC) <quic_c_sbhanu@quicinc.com>
> Cc: adrian.hunter@intel.com; agross@kernel.org; ulf.hansson@linaro.org;
> p.zabel@pengutronix.de; chris@printf.net; gdjakov@mm-sol.com; linux-
> mmc@vger.kernel.org; linux-arm-msm@vger.kernel.org; linux-
> kernel@vger.kernel.org; Asutosh Das (QUIC) <quic_asutoshd@quicinc.com>;
> Ram Prakash Gupta (QUIC) <quic_rampraka@quicinc.com>; Pradeep
> Pragallapati (QUIC) <quic_pragalla@quicinc.com>; Sarthak Garg (QUIC)
> <quic_sartgarg@quicinc.com>; Nitin Rawat (QUIC)
> <quic_nitirawa@quicinc.com>; Sayali Lokhande (QUIC)
> <quic_sayalil@quicinc.com>
> Subject: Re: [PATCH V2] mmc: sdhci-msm: Reset GCC_SDCC_BCR register for
> SDHC
>
> On Thu 10 Mar 07:40 PST 2022, Shaik Sajida Bhanu wrote:
>
> > Reset GCC_SDCC_BCR register before every fresh initilazation. This
> > will reset whole SDHC-msm controller, clears the previous power
> > control states and avoids, software reset timeout issues as below.
> >
>
> Nice, we've gotten reports about this from time to time.
>
> > [ 5.458061][ T262] mmc1: Reset 0x1 never completed.
> > [ 5.462454][ T262] mmc1: sdhci: ============ SDHCI REGISTER DUMP
> > =========== [ 5.469065][ T262] mmc1: sdhci: Sys addr: 0x00000000 |
> > Version:
> > 0x00007202
> > [ 5.475688][ T262] mmc1: sdhci: Blk size: 0x00000000 | Blk cnt:
> > 0x00000000
> > [ 5.482315][ T262] mmc1: sdhci: Argument: 0x00000000 | Trn mode:
> > 0x00000000
> > [ 5.488927][ T262] mmc1: sdhci: Present: 0x01f800f0 | Host ctl:
> > 0x00000000
> > [ 5.495539][ T262] mmc1: sdhci: Power: 0x00000000 | Blk gap:
> > 0x00000000 [ 5.502162][ T262] mmc1: sdhci: Wake-up: 0x00000000 |
> > Clock: 0x00000003 [ 5.508768][ T262] mmc1: sdhci: Timeout: 0x00000000 |
> Int stat:
> > 0x00000000
> > [ 5.515381][ T262] mmc1: sdhci: Int enab: 0x00000000 | Sig enab:
> > 0x00000000
> > [ 5.521996][ T262] mmc1: sdhci: ACmd stat: 0x00000000 | Slot int:
> > 0x00000000
> > [ 5.528607][ T262] mmc1: sdhci: Caps: 0x362dc8b2 | Caps_1: 0x0000808f
> > [ 5.535227][ T262] mmc1: sdhci: Cmd: 0x00000000 | Max curr: 0x00000000
> > [ 5.541841][ T262] mmc1: sdhci: Resp[0]: 0x00000000 | Resp[1]:
> > 0x00000000
> > [ 5.548454][ T262] mmc1: sdhci: Resp[2]: 0x00000000 | Resp[3]:
> > 0x00000000
> > [ 5.555079][ T262] mmc1: sdhci: Host ctl2: 0x00000000 [ 5.559651][
> > T262] mmc1: sdhci_msm: ----------- VENDOR REGISTER
> > DUMP-----------
> > [ 5.566621][ T262] mmc1: sdhci_msm: DLL sts: 0x00000000 | DLL cfg:
> > 0x6000642c |
> > DLL cfg2: 0x0020a000
> > [ 5.575465][ T262] mmc1: sdhci_msm: DLL cfg3: 0x00000000 | DLL usr ctl:
> > 0x00010800 | DDR cfg: 0x80040873
> > [ 5.584658][ T262] mmc1: sdhci_msm: Vndr func: 0x00018a9c | Vndr func2 :
> > 0xf88218a8 Vndr func3: 0x02626040
>
> Please ignore the line length "limit" and leave these unwrapped.
>
Sure
> >
> > Fixes: 0eb0d9f4de34 ("mmc: sdhci-msm: Initial support for Qualcomm
> > chipsets")
>
> This as well, and please drop the empty line between Fixes: and Signed-off-
> by:.
>
Sure
> >
> > Signed-off-by: Shaik Sajida Bhanu <quic_c_sbhanu@quicinc.com>
> > ---
> >
> > Changes since V1:
> > - Added fixes tag as suggested by Ulf Hansson.
> > - Replaced devm_reset_control_get() with
> > devm_reset_control_get_optional_exclusive() as suggested by
> > Ulf Hansson.
> > ---
> > drivers/mmc/host/sdhci-msm.c | 48
> > ++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 48 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci-msm.c
> > b/drivers/mmc/host/sdhci-msm.c index 50c71e0..cb33c9a 100644
> > --- a/drivers/mmc/host/sdhci-msm.c
> > +++ b/drivers/mmc/host/sdhci-msm.c
> > @@ -17,6 +17,7 @@
> > #include <linux/regulator/consumer.h> #include
> > <linux/interconnect.h> #include <linux/pinctrl/consumer.h>
> > +#include <linux/reset.h>
> >
> > #include "sdhci-pltfm.h"
> > #include "cqhci.h"
> > @@ -284,6 +285,7 @@ struct sdhci_msm_host {
> > bool uses_tassadar_dll;
> > u32 dll_config;
> > u32 ddr_config;
> > + struct reset_control *core_reset;
>
> As you only reset the controller once, during probe, this can be a local
> variable in sdhci_msm_gcc_reset().
Hi,

In future if any requirement to reset gcc , for example if we want to reset gcc as a part of hardware reset then we can use this core_reset right.

Thanks,
Sajida
>
> > bool vqmmc_enabled;
> > };
> >
> > @@ -2482,6 +2484,45 @@ static inline void
> sdhci_msm_get_of_property(struct platform_device *pdev,
> > of_property_read_u32(node, "qcom,dll-config",
> > &msm_host->dll_config); }
> >
> > +static int sdhci_msm_gcc_reset(struct platform_device *pdev,
>
> You don't need pdev here, take a struct deivce * in and pass &pdev->dev.
Ok
>
> > + struct sdhci_host *host)
> > +{
> > + struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> > + struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
> > + int ret = 0;
> > +
> > + msm_host->core_reset =
> > +devm_reset_control_get_optional_exclusive(&pdev->dev,
> "core_reset");
>
> No need to hold onto that, so use the non-devm variant and free the reset at
> the end of the function.
Sorry didn't get this.
Can you please point me any reference for this.
>
> > + if (IS_ERR(msm_host->core_reset)) {
> > + ret = PTR_ERR(msm_host->core_reset);
> > + dev_err(&pdev->dev, "core_reset unavailable (%d)\n", ret);
> > + msm_host->core_reset = NULL;
>
> return dev_err_probe(&pdev->dev, PTR_ERR(msm_host->core_reset),
> "unable to acquire core_reset\n");
>
> > + }
> > + if (msm_host->core_reset) {
>
> If you flip this around as:
>
> if (!msm_host->core_reset)
> return 0;
>
> You don't need to zero-initialize ret, use goto and indent this block.
Sure
>
> > + ret = reset_control_assert(msm_host->core_reset);
> > + if (ret) {
> > + dev_err(&pdev->dev, "core_reset assert failed
> (%d)\n",
> > + ret);
> > + goto out;
>
> return dev_err_probe();
>
Sure
> > + }
> > + /*
> > + * The hardware requirement for delay between
> assert/deassert
> > + * is at least 3-4 sleep clock (32.7KHz) cycles, which comes to
> > + * ~125us (4/32768). To be on the safe side add 200us delay.
> > + */
> > + usleep_range(200, 210);
> > +
> > + ret = reset_control_deassert(msm_host->core_reset);
> > + if (ret) {
> > + dev_err(&pdev->dev, "core_reset deassert failed
> (%d)\n",
> > + ret);
> > + goto out;
>
> return dev_err_probe()
Sure
>
> > + }
> > + usleep_range(200, 210);
>
> The comment above says that we need to hold reset for 125us, is this delay
> in here in error or should the comment above mention that this needs to be
> done after deasserting the reset as well?
Yes we need delay after deasserting the reset as well.
>
> > + }
> > +
> > +out:
> > + return ret;
>
> With above, you can return 0 here.
>
> > +}
> >
> > static int sdhci_msm_probe(struct platform_device *pdev) { @@
> > -2529,6 +2570,13 @@ static int sdhci_msm_probe(struct platform_device
> > *pdev)
> >
> > msm_host->saved_tuning_phase = INVALID_TUNING_PHASE;
> >
> > + ret = sdhci_msm_gcc_reset(pdev, host);
> > + if (ret) {
> > + dev_err(&pdev->dev, "core_reset assert/deassert failed
> (%d)\n",
> > + ret);
>
> You just printed in sdhci_msm_gcc_reset(), no need to print again.
>
> Regards,
> Bjorn
>
Okay Sure
> > + goto pltfm_free;
> > + }
> > +
> > /* Setup SDCC bus voter clock. */
> > msm_host->bus_clk = devm_clk_get(&pdev->dev, "bus");
> > if (!IS_ERR(msm_host->bus_clk)) {
> > --
> > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
> > member of Code Aurora Forum, hosted by The Linux Foundation
> >