[PATCH v3 0/2] Add retry tuning sequence

[PATCH v3 0/2] Add retry tuning sequence

[Judith Mendez]

Due to failures to find failing region issues seen on some
boards, add retry tuning sequence to make the tuning algorithm
more robust. The tuning algorithm will re-execute up to 10
times if there is no failing or passing itapdly.

Due to the same issue above, add prints to the tuning algorithm
to make debugging these corner-cases easier.

Changes since v2:
- Use do while loop instead of while in patch 1/2
- Move initialization of tuning_loop to sdhci_am654_init
- Separate error path in patch 1/2
- Move struct *dev = mmc_dev() to patch 2/2

link to v1:
https://lore.kernel.org/linux-mmc/20240815201542.421653-1-jm@ti.com
link to v2:
https://lore.kernel.org/linux-mmc/20240821192435.1619271-1-jm@ti.com

Judith Mendez (2):
  mmc: sdhci_am654: Add retry tuning
  mmc: sdhci_am654: Add prints to tuning algorithm

 drivers/mmc/host/sdhci_am654.c | 54 +++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 11 deletions(-)


base-commit: 538076ce6b8dfe5e8e8d9d250298030f165d8457
-- 
2.46.0

[PATCH v3 1/2] mmc: sdhci_am654: Add retry tuning

[Judith Mendez]

Add retry tuning up to 10 times if we fail to find
a failing region or no passing itapdly. This is
necessary since some eMMC has been observed to never
find a failing itapdly on the first couple of tuning
iterations, but eventually does. Keep count of current
tuning iteration using tuning_loop. It has been observed
that the tuning algorithm does not need to loop more
than 10 times before finding a failing itapdly.

Signed-off-by: Judith Mendez <jm@ti.com>
---
Changes since v2:
- Use do while loop instead of while in patch 1/2
- Move initialization of tuning_loop to sdhci_am654_init
- Separate error path in patch 1/2
---
 drivers/mmc/host/sdhci_am654.c | 46 ++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 64e10f7c9faa3..13da003363e1d 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -86,6 +86,7 @@
 
 #define CLOCK_TOO_SLOW_HZ	50000000
 #define SDHCI_AM654_AUTOSUSPEND_DELAY	-1
+#define RETRY_TUNING_MAX	10
 
 /* Command Queue Host Controller Interface Base address */
 #define SDHCI_AM654_CQE_BASE_ADDR 0x200
@@ -151,6 +152,7 @@ struct sdhci_am654_data {
 	u32 flags;
 	u32 quirks;
 	bool dll_enable;
+	u32 tuning_loop;
 
 #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
 };
@@ -443,7 +445,7 @@ static u32 sdhci_am654_cqhci_irq(struct sdhci_host *host, u32 intmask)
 #define ITAPDLY_LENGTH 32
 #define ITAPDLY_LAST_INDEX (ITAPDLY_LENGTH - 1)
 
-static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
+static int sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
 			  *fail_window, u8 num_fails, bool circular_buffer)
 {
 	u8 itap = 0, start_fail = 0, end_fail = 0, pass_length = 0;
@@ -453,12 +455,14 @@ static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
 	int prev_fail_end = -1;
 	u8 i;
 
-	if (!num_fails)
-		return ITAPDLY_LAST_INDEX >> 1;
+	if (!num_fails) {
+		/* Retry tuning */
+		return -1;
+	}
 
 	if (fail_window->length == ITAPDLY_LENGTH) {
-		dev_err(dev, "No passing ITAPDLY, return 0\n");
-		return 0;
+		/* Retry tuning */
+		return -1;
 	}
 
 	first_fail_start = fail_window->start;
@@ -494,8 +498,8 @@ static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
 	return (itap > ITAPDLY_LAST_INDEX) ? ITAPDLY_LAST_INDEX >> 1 : itap;
 }
 
-static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
-					       u32 opcode)
+static int sdhci_am654_do_tuning(struct sdhci_host *host,
+				 u32 opcode)
 {
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
@@ -532,13 +536,30 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
 	if (fail_window[fail_index].length != 0)
 		fail_index++;
 
-	itap = sdhci_am654_calculate_itap(host, fail_window, fail_index,
-					  sdhci_am654->dll_enable);
+	return sdhci_am654_calculate_itap(host, fail_window, fail_index,
+					 sdhci_am654->dll_enable);
+}
 
-	sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
+static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
+					       u32 opcode)
+{
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
+	unsigned char timing = host->mmc->ios.timing;
+	int itapdly;
 
+	do {
+		itapdly = sdhci_am654_do_tuning(host, opcode);
+		if (itapdly >= 0)
+			break;
+	} while (++sdhci_am654->tuning_loop < RETRY_TUNING_MAX);
+
+	if (itapdly < 0)
+		return -1;
+
+	sdhci_am654_write_itapdly(sdhci_am654, itapdly, sdhci_am654->itap_del_ena[timing]);
 	/* Save ITAPDLY */
-	sdhci_am654->itap_del_sel[timing] = itap;
+	sdhci_am654->itap_del_sel[timing] = itapdly;
 
 	return 0;
 }
@@ -742,6 +763,9 @@ static int sdhci_am654_init(struct sdhci_host *host)
 	regmap_update_bits(sdhci_am654->base, CTL_CFG_3, TUNINGFORSDR50_MASK,
 			   TUNINGFORSDR50_MASK);
 
+	/* Use to re-execute tuning */
+	sdhci_am654->tuning_loop = 0;
+
 	ret = sdhci_setup_host(host);
 	if (ret)
 		return ret;
-- 
2.46.0

[PATCH v3 2/2] mmc: sdhci_am654: Add prints to tuning algorithm

[Judith Mendez]

Add debug prints to tuning algorithm for debugging.
Also add error print if we fail tuning.

Signed-off-by: Judith Mendez <jm@ti.com>
---
Changes since v2:
- Move struct *dev = mmc_dev() to patch 2/2
---
 drivers/mmc/host/sdhci_am654.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 13da003363e1d..0aa3c40ea6ed8 100644
--- a/drivers/mmc/host/sdhci_am654.c
+++ b/drivers/mmc/host/sdhci_am654.c
@@ -457,11 +457,13 @@ static int sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
 
 	if (!num_fails) {
 		/* Retry tuning */
+		dev_dbg(dev, "No failing region found, retry tuning\n");
 		return -1;
 	}
 
 	if (fail_window->length == ITAPDLY_LENGTH) {
 		/* Retry tuning */
+		dev_dbg(dev, "No passing itapdly, retry tuning\n");
 		return -1;
 	}
 
@@ -505,6 +507,7 @@ static int sdhci_am654_do_tuning(struct sdhci_host *host,
 	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
 	unsigned char timing = host->mmc->ios.timing;
 	struct window fail_window[ITAPDLY_LENGTH];
+	struct device *dev = mmc_dev(host->mmc);
 	u8 curr_pass, itap;
 	u8 fail_index = 0;
 	u8 prev_pass = 1;
@@ -525,6 +528,7 @@ static int sdhci_am654_do_tuning(struct sdhci_host *host,
 		if (!curr_pass) {
 			fail_window[fail_index].end = itap;
 			fail_window[fail_index].length++;
+			dev_dbg(dev, "Failed itapdly=%d\n", itap);
 		}
 
 		if (curr_pass && !prev_pass)
@@ -546,6 +550,7 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
 	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
 	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
 	unsigned char timing = host->mmc->ios.timing;
+	struct device *dev = mmc_dev(host->mmc);
 	int itapdly;
 
 	do {
@@ -554,9 +559,12 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
 			break;
 	} while (++sdhci_am654->tuning_loop < RETRY_TUNING_MAX);
 
-	if (itapdly < 0)
+	if (itapdly < 0) {
+		dev_err(dev, "Failed to find itapdly, fail tuning\n");
 		return -1;
+	}
 
+	dev_dbg(dev, "Passed tuning, final itapdly=%d\n", itapdly);
 	sdhci_am654_write_itapdly(sdhci_am654, itapdly, sdhci_am654->itap_del_ena[timing]);
 	/* Save ITAPDLY */
 	sdhci_am654->itap_del_sel[timing] = itapdly;
-- 
2.46.0

Re: [PATCH v3 1/2] mmc: sdhci_am654: Add retry tuning

[Adrian Hunter]

On 27/08/24 00:04, Judith Mendez wrote:
> Add retry tuning up to 10 times if we fail to find
> a failing region or no passing itapdly. This is
> necessary since some eMMC has been observed to never
> find a failing itapdly on the first couple of tuning
> iterations, but eventually does. Keep count of current
> tuning iteration using tuning_loop. It has been observed
> that the tuning algorithm does not need to loop more
> than 10 times before finding a failing itapdly.
> 
> Signed-off-by: Judith Mendez <jm@ti.com>

Still doesn't compile:

  CC [M]  drivers/mmc/host/sdhci_am654.o
drivers/mmc/host/sdhci_am654.c: In function ‘sdhci_am654_calculate_itap’:
drivers/mmc/host/sdhci_am654.c:453:24: error: unused variable ‘dev’ [-Werror=unused-variable]
  453 |         struct device *dev = mmc_dev(host->mmc);
      |                        ^~~
cc1: all warnings being treated as errors

Fix that and you can add:

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
> Changes since v2:
> - Use do while loop instead of while in patch 1/2
> - Move initialization of tuning_loop to sdhci_am654_init
> - Separate error path in patch 1/2
> ---
>  drivers/mmc/host/sdhci_am654.c | 46 ++++++++++++++++++++++++++--------
>  1 file changed, 35 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index 64e10f7c9faa3..13da003363e1d 100644
> --- a/drivers/mmc/host/sdhci_am654.c
> +++ b/drivers/mmc/host/sdhci_am654.c
> @@ -86,6 +86,7 @@
>  
>  #define CLOCK_TOO_SLOW_HZ	50000000
>  #define SDHCI_AM654_AUTOSUSPEND_DELAY	-1
> +#define RETRY_TUNING_MAX	10
>  
>  /* Command Queue Host Controller Interface Base address */
>  #define SDHCI_AM654_CQE_BASE_ADDR 0x200
> @@ -151,6 +152,7 @@ struct sdhci_am654_data {
>  	u32 flags;
>  	u32 quirks;
>  	bool dll_enable;
> +	u32 tuning_loop;
>  
>  #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
>  };
> @@ -443,7 +445,7 @@ static u32 sdhci_am654_cqhci_irq(struct sdhci_host *host, u32 intmask)
>  #define ITAPDLY_LENGTH 32
>  #define ITAPDLY_LAST_INDEX (ITAPDLY_LENGTH - 1)
>  
> -static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
> +static int sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
>  			  *fail_window, u8 num_fails, bool circular_buffer)
>  {
>  	u8 itap = 0, start_fail = 0, end_fail = 0, pass_length = 0;
> @@ -453,12 +455,14 @@ static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
>  	int prev_fail_end = -1;
>  	u8 i;
>  
> -	if (!num_fails)
> -		return ITAPDLY_LAST_INDEX >> 1;
> +	if (!num_fails) {
> +		/* Retry tuning */
> +		return -1;
> +	}
>  
>  	if (fail_window->length == ITAPDLY_LENGTH) {
> -		dev_err(dev, "No passing ITAPDLY, return 0\n");
> -		return 0;
> +		/* Retry tuning */
> +		return -1;
>  	}
>  
>  	first_fail_start = fail_window->start;
> @@ -494,8 +498,8 @@ static u32 sdhci_am654_calculate_itap(struct sdhci_host *host, struct window
>  	return (itap > ITAPDLY_LAST_INDEX) ? ITAPDLY_LAST_INDEX >> 1 : itap;
>  }
>  
> -static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
> -					       u32 opcode)
> +static int sdhci_am654_do_tuning(struct sdhci_host *host,
> +				 u32 opcode)
>  {
>  	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>  	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
> @@ -532,13 +536,30 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
>  	if (fail_window[fail_index].length != 0)
>  		fail_index++;
>  
> -	itap = sdhci_am654_calculate_itap(host, fail_window, fail_index,
> -					  sdhci_am654->dll_enable);
> +	return sdhci_am654_calculate_itap(host, fail_window, fail_index,
> +					 sdhci_am654->dll_enable);
> +}
>  
> -	sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
> +static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
> +					       u32 opcode)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
> +	unsigned char timing = host->mmc->ios.timing;
> +	int itapdly;
>  
> +	do {
> +		itapdly = sdhci_am654_do_tuning(host, opcode);
> +		if (itapdly >= 0)
> +			break;
> +	} while (++sdhci_am654->tuning_loop < RETRY_TUNING_MAX);
> +
> +	if (itapdly < 0)
> +		return -1;
> +
> +	sdhci_am654_write_itapdly(sdhci_am654, itapdly, sdhci_am654->itap_del_ena[timing]);
>  	/* Save ITAPDLY */
> -	sdhci_am654->itap_del_sel[timing] = itap;
> +	sdhci_am654->itap_del_sel[timing] = itapdly;
>  
>  	return 0;
>  }
> @@ -742,6 +763,9 @@ static int sdhci_am654_init(struct sdhci_host *host)
>  	regmap_update_bits(sdhci_am654->base, CTL_CFG_3, TUNINGFORSDR50_MASK,
>  			   TUNINGFORSDR50_MASK);
>  
> +	/* Use to re-execute tuning */
> +	sdhci_am654->tuning_loop = 0;
> +
>  	ret = sdhci_setup_host(host);
>  	if (ret)
>  		return ret;