Re: [PATCH v1 1/2] ufs: core: Configure only active lanes during link

[Palash Kambar <palash.kambar@oss.qualcomm.com>]

On 3/11/2026 12:23 PM, Shawn Lin wrote:
> Hi Palash
> 
> 在 2026/03/11 星期三 14:09, palash.kambar@oss.qualcomm.com 写道:
>> From: Palash Kambar <palash.kambar@oss.qualcomm.com>
>>
>> The number of active lanes detected during UFS link startup can be
> 
> connected lanes(which is used in the code blow) or active lanes? There
> are different primitives in UniPro context.

Yes, I meant connected lanes, will fix comment.

> 
>> fewer than the lanes specified in the device tree. The current driver
>> logic attempts to configure all lanes defined in the device tree,
>> regardless of their actual availability. This mismatch may cause
>> failures during power mode changes.
>>
> 
> It sounds vague, how it causes failures, could you quote some clue from
> spec?

There was a negotiation mismatch for connected lanes during
link startup phase. So when host sends power mode change(PMC) after
UFS link startup, device returns a failure for PMC command with WR_ERROR_CAP
due to mismatch in the connected lane capability between host and device. 

> 
>> Hence, add check to identify only the lanes that were successfully
>> discovered during link startup, to warn on power mode change errors
>> caused by mismatched lane counts.
>>
>> Signed-off-by: Palash Kambar <palash.kambar@oss.qualcomm.com>
>> ---
>>   drivers/ufs/core/ufshcd.c | 39 +++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 39 insertions(+)
>>
>> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
>> index 31950fc51a4c..c956fab32932 100644
>> --- a/drivers/ufs/core/ufshcd.c
>> +++ b/drivers/ufs/core/ufshcd.c
>> @@ -5035,6 +5035,42 @@ void ufshcd_update_evt_hist(struct ufs_hba *hba, u32 id, u32 val)
>>   }
>>   EXPORT_SYMBOL_GPL(ufshcd_update_evt_hist);
>>   +static int ufshcd_get_connected_tx_lanes(struct ufs_hba *hba, u32 *tx_lanes)
>> +{
>> +    return ufshcd_dme_get(hba,
>> +                  UIC_ARG_MIB(PA_CONNECTEDTXDATALANES), tx_lanes);
>> +}
>> +
>> +static int ufshcd_get_connected_rx_lanes(struct ufs_hba *hba, u32 *rx_lanes)
>> +{
>> +    return ufshcd_dme_get(hba,
>> +                  UIC_ARG_MIB(PA_CONNECTEDRXDATALANES), rx_lanes);
>> +}
>> +
>> +static void ufshcd_validate_link_params(struct ufs_hba *hba)
>> +{
>> +    int val = 0;
>> +
>> +    if (ufshcd_get_connected_tx_lanes(hba, &val))
>> +        return;
>> +
>> +    if (val != hba->lanes_per_direction) {
>> +        dev_err(hba->dev, "Tx lane mismatch [config,reported] [%d,%d]\n",
>> +            hba->lanes_per_direction, val);
>> +        return;
>> +    }
>> +
>> +    val = 0;
>> +
>> +    if (ufshcd_get_connected_rx_lanes(hba, &val))
>> +        return;
>> +
>> +    if (val != hba->lanes_per_direction) {
>> +        dev_err(hba->dev, "Rx lane mismatch [config,reported] [%d,%d]\n",
>> +            hba->lanes_per_direction, val);
>> +    }
>> +}
>> +
>>   /**
>>    * ufshcd_link_startup - Initialize unipro link startup
>>    * @hba: per adapter instance
>> @@ -5108,6 +5144,9 @@ static int ufshcd_link_startup(struct ufs_hba *hba)
>>               goto out;
>>       }
>>   +    /* Check successfully detected lanes */
>> +    ufshcd_validate_link_params(hba);
>> +
>>       /* Include any host controller configuration via UIC commands */
>>       ret = ufshcd_vops_link_startup_notify(hba, POST_CHANGE);
>>       if (ret)
>>