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

Judith Mendez posted 2 patches 1 year, 5 months ago
There is a newer version of this series
[PATCH 1/2] mmc: sdhci_am654: Add retry tuning
Posted by Judith Mendez 1 year, 5 months ago 
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's have been observed to never
find a failing itapdly on the first couple of tuning
iterations, but eventually do. It 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>
---
 drivers/mmc/host/sdhci_am654.c | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
index 64e10f7c9faa3..c3d485bd4d553 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)
 };
@@ -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;
@@ -504,6 +508,7 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
 	u8 curr_pass, itap;
 	u8 fail_index = 0;
 	u8 prev_pass = 1;
+	int ret;
 
 	memset(fail_window, 0, sizeof(fail_window));
 
@@ -532,10 +537,20 @@ 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);
+	ret = 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]);
+	if (ret >= 0) {
+		itap = ret;
+		sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
+	} else {
+		if (sdhci_am654->tuning_loop < RETRY_TUNING_MAX) {
+			sdhci_am654->tuning_loop++;
+			sdhci_am654_platform_execute_tuning(host, opcode);
+		} else {
+			return -1;
+		}
+	}
 
 	/* Save ITAPDLY */
 	sdhci_am654->itap_del_sel[timing] = itap;
@@ -908,6 +923,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
 		goto err_pltfm_free;
 	}
 
+	sdhci_am654->tuning_loop = 0;
 	host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
 
 	pm_runtime_get_noresume(dev);
-- 
2.46.0
Re: [PATCH 1/2] mmc: sdhci_am654: Add retry tuning
Posted by Adrian Hunter 1 year, 5 months ago 
On 15/08/24 23:15, 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's have been observed to never
> find a failing itapdly on the first couple of tuning
> iterations, but eventually do. It 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>
> ---
>  drivers/mmc/host/sdhci_am654.c | 30 +++++++++++++++++++++++-------
>  1 file changed, 23 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
> index 64e10f7c9faa3..c3d485bd4d553 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)
>  };
> @@ -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;
> @@ -504,6 +508,7 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
>  	u8 curr_pass, itap;
>  	u8 fail_index = 0;
>  	u8 prev_pass = 1;
> +	int ret;
>  
>  	memset(fail_window, 0, sizeof(fail_window));
>  
> @@ -532,10 +537,20 @@ 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);
> +	ret = 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]);
> +	if (ret >= 0) {
> +		itap = ret;
> +		sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
> +	} else {
> +		if (sdhci_am654->tuning_loop < RETRY_TUNING_MAX) {
> +			sdhci_am654->tuning_loop++;
> +			sdhci_am654_platform_execute_tuning(host, opcode);

The kernel uses very small stack size, so recursive function calls
should not be used.  It would be better to put the loop in a separate
function, or add a retry: label and goto retry.

> +		} else {
> +			return -1;
> +		}
> +	}
>  
>  	/* Save ITAPDLY */
>  	sdhci_am654->itap_del_sel[timing] = itap;
> @@ -908,6 +923,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>  		goto err_pltfm_free;
>  	}
>  
> +	sdhci_am654->tuning_loop = 0;

So this is 10 retries ever, since sdhci_am654->tuning_loop is never
set back to 0.  Is that the intention?

>  	host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>  
>  	pm_runtime_get_noresume(dev);
Re: [PATCH 1/2] mmc: sdhci_am654: Add retry tuning
Posted by Judith Mendez 1 year, 5 months ago 
Hi Adrian,

On 8/21/24 12:37 AM, Adrian Hunter wrote:
> On 15/08/24 23:15, 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's have been observed to never
>> find a failing itapdly on the first couple of tuning
>> iterations, but eventually do. It 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>
>> ---
>>   drivers/mmc/host/sdhci_am654.c | 30 +++++++++++++++++++++++-------
>>   1 file changed, 23 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
>> index 64e10f7c9faa3..c3d485bd4d553 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)
>>   };
>> @@ -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;
>> @@ -504,6 +508,7 @@ static int sdhci_am654_platform_execute_tuning(struct sdhci_host *host,
>>   	u8 curr_pass, itap;
>>   	u8 fail_index = 0;
>>   	u8 prev_pass = 1;
>> +	int ret;
>>   
>>   	memset(fail_window, 0, sizeof(fail_window));
>>   
>> @@ -532,10 +537,20 @@ 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);
>> +	ret = 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]);
>> +	if (ret >= 0) {
>> +		itap = ret;
>> +		sdhci_am654_write_itapdly(sdhci_am654, itap, sdhci_am654->itap_del_ena[timing]);
>> +	} else {
>> +		if (sdhci_am654->tuning_loop < RETRY_TUNING_MAX) {
>> +			sdhci_am654->tuning_loop++;
>> +			sdhci_am654_platform_execute_tuning(host, opcode);
> 
> The kernel uses very small stack size, so recursive function calls
> should not be used.  It would be better to put the loop in a separate
> function, or add a retry: label and goto retry.

Ok, can change to this method, I was not sure of recursive function
call but had opted for that since the code was to be simpler.

> 
>> +		} else {
>> +			return -1;
>> +		}
>> +	}
>>   
>>   	/* Save ITAPDLY */
>>   	sdhci_am654->itap_del_sel[timing] = itap;
>> @@ -908,6 +923,7 @@ static int sdhci_am654_probe(struct platform_device *pdev)
>>   		goto err_pltfm_free;
>>   	}
>>   
>> +	sdhci_am654->tuning_loop = 0;
> 
> So this is 10 retries ever, since sdhci_am654->tuning_loop is never
> set back to 0.  Is that the intention?

Yes, maximum of 10 re-tries. So far we have only seen issues during
boot.

~ Judith

> 
>>   	host->mmc_host_ops.execute_tuning = sdhci_am654_execute_tuning;
>>   
>>   	pm_runtime_get_noresume(dev);
>
Re: [PATCH 1/2] mmc: sdhci_am654: Add retry tuning
Posted by Judith Mendez 1 year, 5 months ago 
Hi all,

On 8/15/24 3:15 PM, 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's have been observed to never
> find a failing itapdly on the first couple of tuning
> iterations, but eventually do. It been observed that the
> tuning algorithm does not need to loop more than 10 times
> before finding a failing itapdly.

Will fix-up this commit message as well, there has only
been one case like this so far.

~ Judith

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