[PATCH 5.4 12/86] mmc: sdhci-xenon: fix 1.8v regulator stabilization

Greg Kroah-Hartman
2021-01-26T08:49:09Z

From: Alex Leibovich <alexl@marvell.com>

commit 1a3ed0dc3594d99ff341ec63865a40519ea24b8d upstream.

Automatic Clock Gating is a feature used for the power consumption
optimisation. It turned out that during early init phase it may prevent the
stable voltage switch to 1.8V - due to that on some platforms an endless
printout in dmesg can be observed: "mmc1: 1.8V regulator output did not
became stable" Fix the problem by disabling the ACG at very beginning of
the sdhci_init and let that be enabled later.

Fixes: 3a3748dba881 ("mmc: sdhci-xenon: Add Marvell Xenon SDHC core functionality")
Signed-off-by: Alex Leibovich <alexl@marvell.com>
Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Cc: stable@vger.kernel.org
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20201211141656.24915-1-mw@semihalf.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mmc/host/sdhci-xenon.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/mmc/host/sdhci-xenon.c
+++ b/drivers/mmc/host/sdhci-xenon.c
@@ -167,7 +167,12 @@ static void xenon_reset_exit(struct sdhc
/* Disable tuning request and auto-retuning again */
xenon_retune_setup(host);

- xenon_set_acg(host, true);
+ /*
+ * The ACG should be turned off at the early init time, in order
+ * to solve a possible issues with the 1.8V regulator stabilization.
+ * The feature is enabled in later stage.
+ */
+ xenon_set_acg(host, false);

xenon_set_sdclk_off_idle(host, sdhc_id, false);