On 03/03/17 10:18, Yangbo Lu wrote:
> There was a mdelay between tuning cycles which is removed since
> eMMC spec didn't require that. However it's observed that eSDHC
> needed this delay for HS200 successful tuning. Maybe it's also
> needed for some other controllers. This patch is to add a quirk
> to fix it.
>
> Fixes: 197160d52e85 ("mmc: sdhci: remove mdelay in eMMC tuning")
> Signed-off-by: Yangbo Lu <yangbo.lu@xxxxxxx>
> ---
I would prefer to do something like this:
---
From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Date: Thu, 23 Mar 2017 08:54:06 +0200
Subject: [PATCH] mmc: sdhci: Control the delay between tuning commands
The delay between tuning commands for SD cards is not part of the
specification. A driver that needs it probably needs it for eMMC too,
whereas most drivers would probably like to set it to 0. Make it a
host member (host->tuning_delay) that defaults to the existing behaviour.
Drivers can set it to zero to eliminate the delay, or set it to a positive
value to always have a delay.
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
drivers/mmc/host/sdhci.c | 11 ++++++++---
drivers/mmc/host/sdhci.h | 1 +
2 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index a33102fc800b..2fc33485df1d 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2100,9 +2100,9 @@ static void __sdhci_execute_tuning(struct sdhci_host *host, u32 opcode)
break;
}
- /* eMMC spec does not require a delay between tuning cycles */
- if (opcode == MMC_SEND_TUNING_BLOCK)
- mdelay(1);
+ /* Spec does not require a delay between tuning cycles */
+ if (host->tuning_delay > 0)
+ mdelay(host->tuning_delay);
}
pr_info("%s: Tuning failed, falling back to fixed sampling clock\n",
@@ -2164,6 +2164,9 @@ int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
host->mmc->retune_period = tuning_count;
+ if (host->tuning_delay < 0)
+ host->tuning_delay = opcode == MMC_SEND_TUNING_BLOCK;
+
sdhci_start_tuning(host);
__sdhci_execute_tuning(host, opcode);
@@ -3108,6 +3111,8 @@ struct sdhci_host *sdhci_alloc_host(struct device *dev,
host->cqe_ier = SDHCI_CQE_INT_MASK;
host->cqe_err_ier = SDHCI_CQE_INT_ERR_MASK;
+ host->tuning_delay = -1;
+
return host;
}
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 35b41da0a636..b0f416fc9548 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -538,6 +538,7 @@ struct sdhci_host {
#define SDHCI_TUNING_MODE_1 0
#define SDHCI_TUNING_MODE_2 1
#define SDHCI_TUNING_MODE_3 2
+ int tuning_delay; /* Delay (ms) between tuning commands */
unsigned long private[0] ____cacheline_aligned;
};
--
1.9.1
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