Re: [PATCH] sdhci: Forward EPROBE_DEFER on vmmc and vqmmc regulators

From: Mike Looijmans
Date: Thu Mar 27 2014 - 13:48:12 EST


On 26-3-2014 16:09, Georgi Djakov wrote:
On 03/07/2014 04:18 PM, Mike Looijmans wrote:
If vmmc or vqmmc regulators are controlled by an I2C device, the
request for the regulator is likely to fail because the I2C bus has
not been probed yet. The sdhci then incorrectly assumes that the user
never wanted to use a regulator anyway and continues without ever
enabling or configuring the required regulator.

To solve this, when a required voltage regulator returns
EPROBE_DEFER, signalling that the regulator exists but is not
available yet, forward this error to the probe method instead
of simply assuming that the user never wanted to use a regulator
anyway.

Tested on a custom board that has an I2C regulator for one of the sdhcis
and no regulators at all for the other. This patch enables such a system
to work correctly.
---
drivers/mmc/host/sdhci.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 34aef81..43b90c1 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2972,6 +2972,8 @@ int sdhci_add_host(struct sdhci_host *host)
host->vqmmc = regulator_get_optional(mmc_dev(mmc), "vqmmc");
if (IS_ERR_OR_NULL(host->vqmmc)) {
if (PTR_ERR(host->vqmmc) < 0) {
+ if (PTR_ERR(host->vqmmc) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
pr_info("%s: no vqmmc regulator found\n",
mmc_hostname(mmc));
host->vqmmc = NULL;
@@ -3048,8 +3050,10 @@ int sdhci_add_host(struct sdhci_host *host)
host->vmmc = regulator_get_optional(mmc_dev(mmc), "vmmc");
if (IS_ERR_OR_NULL(host->vmmc)) {
if (PTR_ERR(host->vmmc) < 0) {
- pr_info("%s: no vmmc regulator found\n",
- mmc_hostname(mmc));
+ if (PTR_ERR(host->vmmc) == -EPROBE_DEFER)
+ return -EPROBE_DEFER;
+ pr_info("%s: no vmmc regulator found (%d)\n",

I suggest using %ld here. The rest looks fine to me! Thanks!

Does this mean you're waiting for a patch v2 that I should submit?


+ mmc_hostname(mmc), PTR_ERR(host->vmmc));
host->vmmc = NULL;
}
}


BR,
Georgi



--
Mike Looijmans
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/