Re: [PATCH 3/5] mmc: cavium: Prevent crash with incomplete DT

[Ulf Hansson]

On 16 May 2017 at 11:36, Jan Glauber <jglauber@xxxxxxxxxx> wrote:
> In case the DT specifies neither a regulator nor a gpio
> for the shared power the driver will crash accessing the regulator.
> Prevent the crash by checking the regulator before use.
>
> As the MMC devices would likely not be usable without power
> check for that condition during probe and print a warning.
>
> Signed-off-by: Jan Glauber <jglauber@xxxxxxxxxx>
> ---
>  drivers/mmc/host/cavium.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/host/cavium.c b/drivers/mmc/host/cavium.c
> index 58b51ba..63f96dc 100644
> --- a/drivers/mmc/host/cavium.c
> +++ b/drivers/mmc/host/cavium.c
> @@ -839,14 +839,14 @@ static void cvm_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>                 cvm_mmc_reset_bus(slot);
>                 if (host->global_pwr_gpiod)
>                         host->set_shared_power(host, 0);
> -               else
> +               else if (mmc->supply.vmmc)

Please do this instead:

else if (!IS_ERR(mmc->supply.vmmc))

>                         mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, 0);
>                 break;
>
>         case MMC_POWER_UP:
>                 if (host->global_pwr_gpiod)
>                         host->set_shared_power(host, 1);
> -               else
> +               else if (mmc->supply.vmmc)

Ditto

>                         mmc_regulator_set_ocr(mmc, mmc->supply.vmmc, ios->vdd);
>                 break;
>         }
> @@ -976,6 +976,7 @@ static int cvm_mmc_of_parse(struct device *dev, struct cvm_mmc_slot *slot)
>                  * Legacy Octeon firmware has no regulator entry, fall-back to
>                  * a hard-coded voltage to get a sane OCR.
>                  */
> +               mmc->supply.vmmc = NULL;

... and then you shall remove this.

>                 mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
>         } else {
>                 ret = mmc_regulator_get_ocrmask(mmc->supply.vmmc);
> @@ -983,6 +984,9 @@ static int cvm_mmc_of_parse(struct device *dev, struct cvm_mmc_slot *slot)
>                         mmc->ocr_avail = ret;
>         }
>
> +       if (!mmc->supply.vmmc && !slot->host->global_pwr_gpiod)
> +               dev_warn(dev, "Missing power regulator or gpio, device may not work.\n");
> +

While you re-spins this, I suggest you to also convert to use the
mmc_regulator_get_supply() API.
That should simply the code a bit and also avoid you from needing to
print anything like this above, as there are already some printing
being done in mmc_regulator_get_supply().

>         /* Common MMC bindings */
>         ret = mmc_of_parse(mmc);
>         if (ret)
> --
> 2.9.0.rc0.21.g7777322
>

Kind regards
Uffe