Re: [bug report] mmc: sdhci: Allow platform controlled voltage switching

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Hi,

Thanks for reporting this issue. Will post a patch to fix this issue.

Thanks
Veera

On 7/9/2020 3:13 PM, dan.carpenter@xxxxxxxxxx wrote:
Hello Vijay Viswanath,

The patch f870b6d480d3: "mmc: sdhci: Allow platform controlled
voltage switching" from Jun 23, 2020, leads to the following static
checker warning:

	drivers/mmc/host/sdhci.c:4396 sdhci_setup_host()
	warn: potential ERR_PTR parameter dereference 'mmc->supply.vqmmc'

drivers/mmc/host/sdhci.c
   4375          if (host->caps & SDHCI_CAN_DO_HISPD)
   4376                  mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED;
   4377
   4378          if ((host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) &&
   4379              mmc_card_is_removable(mmc) &&
   4380              mmc_gpio_get_cd(host->mmc) < 0)
   4381                  mmc->caps |= MMC_CAP_NEEDS_POLL;
   4382
   4383          if (!IS_ERR(mmc->supply.vqmmc)) {
   4384                  if (enable_vqmmc) {
   4385                          ret = regulator_enable(mmc->supply.vqmmc);
   4386                          if (ret) {
   4387                                  pr_warn("%s: Failed to enable vqmmc regulator: %d\n",
   4388                                          mmc_hostname(mmc), ret);
   4389                                  mmc->supply.vqmmc = ERR_PTR(-EINVAL);
                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This is an error pointer.

   4390                          }
   4391                          host->sdhci_core_to_disable_vqmmc = !ret;
   4392                  }
   4393
   4394                  /* If vqmmc provides no 1.8V signalling, then there's no UHS */
   4395                  if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000,
                                                             ^^^^^^^^^^^^^^^^^
It is dereferenced inside the function and will crash.

   4396                                                      1950000))
   4397                          host->caps1 &= ~(SDHCI_SUPPORT_SDR104 |
   4398                                           SDHCI_SUPPORT_SDR50 |
   4399                                           SDHCI_SUPPORT_DDR50);
   4400
   4401                  /* In eMMC case vqmmc might be a fixed 1.8V regulator */
   4402                  if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 2700000,
   4403                                                      3600000))
   4404                          host->flags &= ~SDHCI_SIGNALING_330;
   4405          }
   4406

regards,
dan carpenter



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