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* [PATCH v6] mmc: sdhci: clarify the get_timeout_clock callback
@ 2017-03-24  7:50 Shawn Lin
  2017-03-24  8:07 ` Adrian Hunter
  2017-03-24  9:20 ` Ulf Hansson
  0 siblings, 2 replies; 3+ messages in thread
From: Shawn Lin @ 2017-03-24  7:50 UTC (permalink / raw)
  To: Adrian Hunter, Ulf Hansson; +Cc: linux-mmc, Masahiro Yamada, Shawn Lin

Currently the get_timeout_clock callback doesn't clearly
have a statement that it needs the variant drivers to return
the timeout clock rate in kHz if the SDHCI_TIMEOUT_CLK_UNIT
isn't present, otherwise the variant drivers should return it
in MHz. It's also very likely that further variant drivers which
are going to use this callback will be confused by this situation.
Given the fact that moderm sdhci variant hosts are very prone to get
the timeout clock from common clock framework (actually the only three
users did that), it's more natural to return the value in Hz and we
make an explicit comment there. Then we put the unit conversion inside
the sdhci core. Thus will improve the code and prevent further misuses.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Reported-by: Anssi Hannula <anssi.hannula@bitwise.fi>
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Changes in v6:
- rebase on Ulf's next
- improve some commit msg and add Anssi's tag

Changes in v5:
- fix typo
- remove unlikely

Changes in v4:
- rebased on -next
- add Masahiro's ack for sdhci-cadence

Changes in v3:
- squash all the patches into one to keep bisectability
- fix wrong return value of sdhci-cadence
- slight improve the condition check to avoid the complaint of
  checkpatch

Changes in v2:
- fix the comment and make it return in Hz

 drivers/mmc/host/sdhci-cadence.c   |  4 ++--
 drivers/mmc/host/sdhci-of-arasan.c | 17 +----------------
 drivers/mmc/host/sdhci.c           | 16 +++++++++-------
 drivers/mmc/host/sdhci.h           |  1 +
 4 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
index 48f6419..07a27dc 100644
--- a/drivers/mmc/host/sdhci-cadence.c
+++ b/drivers/mmc/host/sdhci-cadence.c
@@ -105,9 +105,9 @@ static unsigned int sdhci_cdns_get_timeout_clock(struct sdhci_host *host)
 {
 	/*
 	 * Cadence's spec says the Timeout Clock Frequency is the same as the
-	 * Base Clock Frequency.  Divide it by 1000 to return a value in kHz.
+	 * Base Clock Frequency.
 	 */
-	return host->max_clk / 1000;
+	return host->max_clk;
 }
 
 static void sdhci_cdns_set_emmc_mode(struct sdhci_cdns_priv *priv, u32 mode)
diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
index 61accf0..ea6b36c 100644
--- a/drivers/mmc/host/sdhci-of-arasan.c
+++ b/drivers/mmc/host/sdhci-of-arasan.c
@@ -157,21 +157,6 @@ static int sdhci_arasan_syscon_write(struct sdhci_host *host,
 	return ret;
 }
 
-static unsigned int sdhci_arasan_get_timeout_clock(struct sdhci_host *host)
-{
-	unsigned long freq;
-	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
-
-	/* SDHCI timeout clock is in kHz */
-	freq = DIV_ROUND_UP(clk_get_rate(pltfm_host->clk), 1000);
-
-	/* or in MHz */
-	if (host->caps & SDHCI_TIMEOUT_CLK_UNIT)
-		freq = DIV_ROUND_UP(freq, 1000);
-
-	return freq;
-}
-
 static void sdhci_arasan_set_clock(struct sdhci_host *host, unsigned int clock)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
@@ -280,7 +265,7 @@ static int sdhci_arasan_voltage_switch(struct mmc_host *mmc,
 static struct sdhci_ops sdhci_arasan_ops = {
 	.set_clock = sdhci_arasan_set_clock,
 	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
-	.get_timeout_clock = sdhci_arasan_get_timeout_clock,
+	.get_timeout_clock = sdhci_pltfm_clk_get_max_clock,
 	.set_bus_width = sdhci_set_bus_width,
 	.reset = sdhci_arasan_reset,
 	.set_uhs_signaling = sdhci_set_uhs_signaling,
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index a33102f..0d4485d 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -3390,20 +3390,22 @@ int sdhci_setup_host(struct sdhci_host *host)
 	if (!(host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)) {
 		host->timeout_clk = (host->caps & SDHCI_TIMEOUT_CLK_MASK) >>
 					SDHCI_TIMEOUT_CLK_SHIFT;
+
+		if (host->caps & SDHCI_TIMEOUT_CLK_UNIT)
+			host->timeout_clk *= 1000;
+
 		if (host->timeout_clk == 0) {
-			if (host->ops->get_timeout_clock) {
-				host->timeout_clk =
-					host->ops->get_timeout_clock(host);
-			} else {
+			if (!host->ops->get_timeout_clock) {
 				pr_err("%s: Hardware doesn't specify timeout clock frequency.\n",
 					mmc_hostname(mmc));
 				ret = -ENODEV;
 				goto undma;
 			}
-		}
 
-		if (host->caps & SDHCI_TIMEOUT_CLK_UNIT)
-			host->timeout_clk *= 1000;
+			host->timeout_clk =
+				DIV_ROUND_UP(host->ops->get_timeout_clock(host),
+					     1000);
+		}
 
 		if (override_timeout_clk)
 			host->timeout_clk = override_timeout_clk;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 35b41da..fdb5d7e 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -561,6 +561,7 @@ struct sdhci_ops {
 	int		(*enable_dma)(struct sdhci_host *host);
 	unsigned int	(*get_max_clock)(struct sdhci_host *host);
 	unsigned int	(*get_min_clock)(struct sdhci_host *host);
+	/* get_timeout_clock should return clk rate in unit of Hz */
 	unsigned int	(*get_timeout_clock)(struct sdhci_host *host);
 	unsigned int	(*get_max_timeout_count)(struct sdhci_host *host);
 	void		(*set_timeout)(struct sdhci_host *host,
-- 
1.9.1



^ permalink raw reply related	[flat|nested] 3+ messages in thread
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2017-03-24  7:50 [PATCH v6] mmc: sdhci: clarify the get_timeout_clock callback Shawn Lin
2017-03-24  8:07 ` Adrian Hunter
2017-03-24  9:20 ` Ulf Hansson

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