From: Wolfram Sang <wsa+renesas@sang-engineering.com>
To: linux-mmc@vger.kernel.org
Cc: linux-renesas-soc@vger.kernel.org,
Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
Wolfram Sang <wsa+renesas@sang-engineering.com>
Subject: [PATCH v2 3/4] mmc: renesas_sdhi: keep SCC clock active when tuning
Date: Tue, 1 Sep 2020 17:02:49 +0200 [thread overview]
Message-ID: <20200901150250.26236-4-wsa+renesas@sang-engineering.com> (raw)
In-Reply-To: <20200901150250.26236-1-wsa+renesas@sang-engineering.com>
Tuning procedure switches to lower frequencies but that will turn the
SCC off and accessing its register then will hang. So, check when we are
tuning and keep the current setup of the external clock if we are doing
so. Note that we still switch to the lower frequency because of the
internal divider. We just make sure to not modify the external clock.
This patch depends on a MMC core patch calling the downgrade function
earlier.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
drivers/mmc/host/renesas_sdhi_core.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index 29148fa25d82..c5cba0a1b112 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -117,8 +117,12 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
unsigned int freq, diff, best_freq = 0, diff_min = ~0;
int i;
- /* tested only on R-Car Gen2+ currently; may work for others */
- if (!(host->pdata->flags & TMIO_MMC_MIN_RCAR2))
+ /*
+ * We simply return the current rate if a) we are not on a R-Car Gen2+
+ * SoC (may work for others, but untested) or b) if the SCC needs its
+ * clock during tuning, so we don't change the external clock setup.
+ */
+ if (!(host->pdata->flags & TMIO_MMC_MIN_RCAR2) || mmc_doing_tune(host->mmc))
return clk_get_rate(priv->clk);
/*
--
2.20.1
next prev parent reply other threads:[~2020-09-01 15:03 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-01 15:02 [PATCH v2 0/4] renesas_sdhi: fix hang when SCC loses its clock Wolfram Sang
2020-09-01 15:02 ` [PATCH v2 1/4] mmc: core: when downgrading HS400, callback into drivers earlier Wolfram Sang
2020-09-01 15:02 ` [PATCH v2 2/4] mmc: core: add a 'doing_init_tune' flag and a 'mmc_doing_tune' helper Wolfram Sang
2020-09-01 15:02 ` Wolfram Sang [this message]
2020-09-01 15:02 ` [PATCH v2 4/4] mmc: core: simplify an expression Wolfram Sang
2020-09-02 9:51 ` [PATCH v2 0/4] renesas_sdhi: fix hang when SCC loses its clock Yoshihiro Shimoda
2020-09-03 8:10 ` Ulf Hansson
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