linux-kernel - Re: [PATCH v3] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and SR1.1

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Message-ID: <f117bc05-893f-4c89-8cb7-3f40a8bfb92d@intel.com>
Date: Tue, 19 Aug 2025 16:21:36 +0300
From: Adrian Hunter <adrian.hunter@...el.com>
To: Andrew Davis <afd@...com>, Judith Mendez <jm@...com>, Ulf Hansson
	<ulf.hansson@...aro.org>
CC: <linux-mmc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] mmc: sdhci_am654: Disable HS400 for AM62P SR1.0 and
 SR1.1

On 18/08/2025 23:38, Andrew Davis wrote:
> On 8/18/25 3:33 PM, Judith Mendez wrote:
>> This adds SDHCI_AM654_QUIRK_DISABLE_HS400 quirk which shall be used
>> to disable HS400 support. AM62P SR1.0 and SR1.1 do not support HS400
>> due to errata i2458 [0] so disable HS400 for these SoC revisions.
>>
>> [0] https://www.ti.com/lit/er/sprz574a/sprz574a.pdf
>> Signed-off-by: Judith Mendez <jm@...com>
>> ---
>> This patch was separated from [0] since it will be merged to
>> different trees anyways.
>>
>> Link to v2:
>> [0] https://lore.kernel.org/linux-mmc/20250807225138.1228333-1-jm@ti.com
>> ---
>>   drivers/mmc/host/sdhci_am654.c | 18 ++++++++++++++++++
>>   1 file changed, 18 insertions(+)
>>
>> diff --git a/drivers/mmc/host/sdhci_am654.c b/drivers/mmc/host/sdhci_am654.c
>> index 8a099508b939..cc8c4145bf2b 100644
>> --- a/drivers/mmc/host/sdhci_am654.c
>> +++ b/drivers/mmc/host/sdhci_am654.c
>> @@ -155,6 +155,7 @@ struct sdhci_am654_data {
>>     #define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
>>   #define SDHCI_AM654_QUIRK_SUPPRESS_V1P8_ENA BIT(1)
>> +#define SDHCI_AM654_QUIRK_DISABLE_HS400 BIT(2)
>>   };
>>     struct window {
>> @@ -764,6 +765,7 @@ static int sdhci_am654_init(struct sdhci_host *host)
>>   {
>>       struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>       struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
>> +    struct device *dev = mmc_dev(host->mmc);
>>       u32 ctl_cfg_2 = 0;
>>       u32 mask;
>>       u32 val;
>> @@ -819,6 +821,12 @@ static int sdhci_am654_init(struct sdhci_host *host)
>>       if (ret)
>>           goto err_cleanup_host;
>>   +    if (sdhci_am654->quirks & SDHCI_AM654_QUIRK_DISABLE_HS400 &&
>> +        host->mmc->caps2 & (MMC_CAP2_HS400 | MMC_CAP2_HS400_ES)) {
>> +        dev_info(dev, "Disable descoped HS400 mode for this silicon revision\n");
> 
> Messages to the user do not need to be imperative, maybe:
> 
> "Disabling HS400 mode not supported on this silicon revision\n"
> 
> Not a blocker,
> 
> Reviewed-by: Andrew Davis <afd@...com>

I agree about the message.  Another possibility:
"HS400 mode is not supported on this silicon revision, disabling it"

Otherwise:

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