linux-kernel - Re: [PATCH v1 4/5] mmc: sdhci_am654: Add ITAPDLYSEL in sdhci_j721e_4bit_set

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Date: Fri, 2 Feb 2024 10:12:43 +0530
From: Vignesh Raghavendra <vigneshr@...com>
To: Andrew Davis <afd@...com>, Judith Mendez <jm@...com>,
        Ulf Hansson
	<ulf.hansson@...aro.org>
CC: Adrian Hunter <adrian.hunter@...el.com>, <linux-mmc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Randolph Sapp <rs@...com>
Subject: Re: [PATCH v1 4/5] mmc: sdhci_am654: Add ITAPDLYSEL in
 sdhci_j721e_4bit_set_clock



On 02/02/24 01:27, Andrew Davis wrote:
> On 1/31/24 3:50 PM, Judith Mendez wrote:
>> Add ITAPDLYSEL to sdhci_j721e_4bit_set_clock function.
>> This allows to set the correct ITAPDLY for timings that
>> do not carry out tuning.
>>
>> Fixes: 1accbced1c32 ("mmc: sdhci_am654: Add Support for 4 bit IP on
>> J721E")
> 
> You are adding this as a new feature, and not having a feature doesn't mean
> the initial patch was broken. If this patch was backported to kernels only
> containing the above patch it would cause more issues, so no need for the
> fixes tags on this nor the last patch.
> 

Not really a new features. Devices Datasheets have always been clear
that static ITAPDLY needs to be configured when tuning isn't performed.
Hence a bug as the initial patch (Fixes line) does enable such
(affected) modes where tuning isn't performed but ITAPDLY isn't set either.

> Andrew
> 
>> Signed-off-by: Judith Mendez <jm@...com>
>> ---
>>   drivers/mmc/host/sdhci_am654.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci_am654.c
>> b/drivers/mmc/host/sdhci_am654.c
>> index 5ac82bc70706..f5dc981c470d 100644
>> --- a/drivers/mmc/host/sdhci_am654.c
>> +++ b/drivers/mmc/host/sdhci_am654.c
>> @@ -321,6 +321,7 @@ static void sdhci_j721e_4bit_set_clock(struct
>> sdhci_host *host,
>>       unsigned char timing = host->mmc->ios.timing;
>>       u32 otap_del_sel;
>>       u32 itap_del_ena;
>> +    u32 itap_del_sel;
>>       u32 mask, val;
>>         /* Setup Output TAP delay */
>> @@ -329,12 +330,17 @@ static void sdhci_j721e_4bit_set_clock(struct
>> sdhci_host *host,
>>       mask = OTAPDLYENA_MASK | OTAPDLYSEL_MASK;
>>       val = (0x1 << OTAPDLYENA_SHIFT) | (otap_del_sel <<
>> OTAPDLYSEL_SHIFT);
>>   +    /* Setup Input TAP delay */
>>       itap_del_ena = sdhci_am654->itap_del_ena[timing];
>> +    itap_del_sel = sdhci_am654->itap_del_sel[timing];
>>   -    mask |= ITAPDLYENA_MASK;
>> -    val |= (itap_del_ena << ITAPDLYENA_SHIFT);
>> +    mask |= ITAPDLYENA_MASK | ITAPDLYSEL_MASK;
>> +    val |= (itap_del_ena << ITAPDLYENA_SHIFT) | (itap_del_sel <<
>> ITAPDLYSEL_SHIFT);
>>   +    regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPCHGWIN_MASK,
>> +               1 << ITAPCHGWIN_SHIFT);
>>       regmap_update_bits(sdhci_am654->base, PHY_CTRL4, mask, val);
>> +    regmap_update_bits(sdhci_am654->base, PHY_CTRL4, ITAPCHGWIN_MASK,
>> 0);
>>         regmap_update_bits(sdhci_am654->base, PHY_CTRL5, CLKBUFSEL_MASK,
>>                  sdhci_am654->clkbuf_sel);

-- 
Regards
Vignesh