Re: [PATCH v5 1/5] mmc: core: Extend mmc_of_parse() to parse CQE bindings

[Veerabhadrarao Badiganti]

On 5/6/2020 10:06 PM, Ulf Hansson wrote:
> On Wed, 6 May 2020 at 15:01, Veerabhadrarao Badiganti
> <vbadigan@xxxxxxxxxxxxxx> wrote:
> > On 4/28/2020 5:26 AM, Chun-Hung Wu wrote:
> > > Parse CQE bindings "supports-cqe" and "disable-cqe-dcmd"
> > > in mmc_of_parse().
> > >
> > > Signed-off-by: Chun-Hung Wu <chun-hung.wu@xxxxxxxxxxxx>
> > > ---
> > >    drivers/mmc/core/host.c | 5 +++++
> > >    1 file changed, 5 insertions(+)
> > >
> > > diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> > > index c876872..47521c6 100644
> > > --- a/drivers/mmc/core/host.c
> > > +++ b/drivers/mmc/core/host.c
> > > @@ -302,6 +302,11 @@ int mmc_of_parse(struct mmc_host *host)
> > >                host->caps2 |= MMC_CAP2_NO_SD;
> > >        if (device_property_read_bool(dev, "no-mmc"))
> > >                host->caps2 |= MMC_CAP2_NO_MMC;
> > > +     if (device_property_read_bool(dev, "supports-cqe"))
> > > +             host->caps2 |= MMC_CAP2_CQE;
> > This change is breaking emmc driver on qcom platforms where this dt
> > property is defined.
> >
> > [    1.543453]  cqhci_deactivate+0xc/0x38
> > [    1.545627]  sdhci_msm_reset+0x40/0x58
> > [    1.549447]  sdhci_do_reset+0x48/0x7c
> > [    1.553180]  __sdhci_read_caps+0x7c/0x214
> > [    1.556913]  sdhci_setup_host+0x58/0xce8
> > [    1.560905]  sdhci_msm_probe+0x588/0x8a4
> > [    1.564900]  platform_drv_probe+0x4c/0xb0
> >
> > So, we cant have this flag defined before sdhci_setup_host().
> >
> > I will have to clear this cap and re-enable it in our initialization.
> Thanks for reporting! I have dropped all the four patches from
> Chun-Hung, so we can figure out how to fix this.
>
> Please help to review the next version of the series.

Thanks Ulf.

Hi Chun-Hung,

On qcom controller CQE also gets reset when SDHC is reset. So we have to 
explicitly disable CQE
by invoking cqhci_deactivate() during sdhc reset

SDHC gets reset in sdhci_setup_host() even before cqe is initialized.
With MMC_CAP2_CQE_DCMD cap set even before sdhci_set_host(), we are 
getting null pointer access with cqhci_deactivate().

If CQE getting reset with SDHC reset is generic (applicable to other 
controllers) then you have revisit your logic.
If its not the case then only qcom driver would get affected.

I see you are updating sdhci-msm.c file as-well. How about including 
below change besides your change?

@@ -1658,6 +1658,8 @@ static int sdhci_msm_cqe_add_host(struct 
sdhci_host *host,
ÂÂÂÂÂÂÂ if (host->caps & SDHCI_CAN_64BIT)
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ host->alloc_desc_sz = 16;

+ÂÂÂÂÂÂ /* Clear the CQE cap during setup host */
+ÂÂÂÂÂÂ msm_host->mmc->caps2 &= ~MMC_CAP2_CQE;
+
ÂÂÂÂÂÂÂ ret = sdhci_setup_host(host);

> > > +     if (!device_property_read_bool(dev, "disable-cqe-dcmd")) {
> > > +             host->caps2 |= MMC_CAP2_CQE_DCMD;
> > > +     }
> > >
> > >        /* Must be after "non-removable" check */
> > >        if (device_property_read_u32(dev, "fixed-emmc-driver-type", &drv_type) == 0) {
> Kind regards
> Uffe