mmc_regulator_get_supply returns -EPROBE_DEFER if either vmmc or
vqmmc regulators had their probing deferred.
vqmmc regulator is needed by UHS to work properly, therefore this
patch checks the value returned by mmc_regulator_get_supply to
make sure we have a reference to both vmmc and vqmmc (if found in
the DT).
Signed-off-by: Fabrizio Castro <fabrizio.castro@xxxxxxxxxxxxxx>
---
I believe this patch is in order for UHS to work properly on the RZ/G1 platforms
as the signal voltage needs to be switched from 3.3V to 1.8V, and therefore we
need to make sure we hold a reference to vqmmc. Without this patch there is a
chance that the regulator driver gets probed later on and therefore we end up
without control over the power regulator. I have seen an RZ/G1E based platform
failing the transition to UHS because of this.
However, there are side effects to it as the mmc devices will be enumerated
in a different order (due to -EPROBE_DEFER), this means this patch would likely
break existing platforms.
Please, let me know your comments.
drivers/mmc/host/tmio_mmc_core.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c
index 88a9435..3df0413 100644
--- a/drivers/mmc/host/tmio_mmc_core.c
+++ b/drivers/mmc/host/tmio_mmc_core.c
@@ -1153,8 +1153,11 @@ static int tmio_mmc_init_ocr(struct tmio_mmc_host *host)
{
struct tmio_mmc_data *pdata = host->pdata;
struct mmc_host *mmc = host->mmc;
+ int err;
- mmc_regulator_get_supply(mmc);
+ err = mmc_regulator_get_supply(mmc);
+ if (err)
+ return err;
/* use ocr_mask if no regulator */
if (!mmc->ocr_avail)
--
2.7.4
