by Can Guo

[permalink] [raw]

Subject: Re: [PATCH v6 08/10] phy: qualcomm: phy-qcom-qmp-ufs: Add High Speed Gear 5 support for SM8550

On 11/30/2023 5:34 PM, Manivannan Sadhasivam wrote:
> On Thu, Nov 30, 2023 at 04:49:12PM +0800, Can Guo wrote:
>>
>>
>> On 11/30/2023 4:38 PM, Manivannan Sadhasivam wrote:
>>> On Thu, Nov 30, 2023 at 04:14:25PM +0800, Can Guo wrote:
>
> [...]
>
>>>>>> +static int qmp_ufs_get_gear_overlay(struct qmp_ufs *qmp, const struct qmp_phy_cfg *cfg)
>>>>>> +{
>>>>>> + u32 max_gear, floor_max_gear = cfg->max_supported_gear;
>>>>>> + int i = NUM_OVERLAY - 1;
>>>>>
>>>>> Just use i directly in the for loop. Also, please rename "i" with "idx" to make
>>>>> it clear.
>>>>
>>>> OK
>>>>
>>>>>
>>>>>> + int ret = -EINVAL;
>>>>>> +
>>>>>> + for (; i >= 0; i --) {
>>>>>
>>>>> i--
>>>>>
>>>>>> + max_gear = cfg->tbls_hs_overlay[i].max_gear;
>>>>>> +
>>>>>> + if (max_gear == 0)
>>>>>> + continue;
>>>>>
>>>>> You are setting max_gear even for targets with a single overlay. How can this
>>>>> become 0?
>>>>
>>>> Say 8550 has two overlays, 8450 has one overlay. We are sweeping all
>>>> overlays as NUM_OVERLAY == 2, so for 8450, there is one overlay initialized,
>>>> another one not initialized (max_gear == 0), we are skipping the one which
>>>> is not initialized.
>>>>
>>>
>>> This is confusing at its best :) Please check for the existence of the actual
>>> table instead. Like,
>>>
>>> for (idx = NUM_OVERLAY - 1; i >= 0, i--) {
>>>
>>> /* Skip if the table is not available */
>>> if (!cfg->tbls_hs_overlay[i].serdes)
>>> continue;
>>>
>>> ...
>>> }
>>
>> We cannot expect overlay must has its own serdes, or tx/rx/pcs, hence I am
>> checking max_gear intead of any specific member.
>>
>
> Hmm, then please add the comment as I suggested above.

Sure

Thanks,
Can Guo.

>
>>>
>>>>>
>>>>>> +
>>>>>> + /* Direct matching, bail */
>>>>>> + if (qmp->submode == max_gear)
>>>>>> + return i;
>>>>>> +
>>>>>> + /* If no direct matching, the lowest gear is the best matching */
>>>>>> + if (max_gear < floor_max_gear) {
>>>>>> + ret = i;
>>>>>> + floor_max_gear = max_gear;
>>>>>> + }
>>>>>> + }
>>>>>> +
>>>>>> + return ret;
>>>>>> +}
>>>>>> +
>>>>>> static void qmp_ufs_init_registers(struct qmp_ufs *qmp, const struct qmp_phy_cfg *cfg)
>>>>>> {
>>>>>> + int i;
>>>>>> + bool apply_overlay = false;
>>>>>> +
>>>>>> + i = qmp_ufs_get_gear_overlay(qmp, cfg);
>>>>>> + if (i >= 0)
>>>>>> + apply_overlay = true;
>>>>>
>>>>> How about?
>>>>>
>>>>> ```
>>>>> int idx;
>>>>>
>>>>> idx = qmp_ufs_get_gear_overlay(qmp, cfg);
>>>>>
>>>>> qmp_ufs_serdes_init(qmp, &cfg->tbls);
>>>>> qmp_ufs_lanes_init(qmp, &cfg->tbls);
>>>>> ...
>>>>>
>>>>> if (idx >= 0) {
>>>>> qmp_ufs_serdes_init(qmp, &cfg->tbls_hs_overlay[idx]);
>>>>> qmp_ufs_lanes_init(qmp, &cfg->tbls_hs_overlay[idx]);
>>>>> ...
>>>>> }
>>>>> ```
>>>>>
>>>>> Since the ordering doesn't matter for init sequence, you can program the overlay
>>>>> tables under a single condition.
>>>>
>>>> We can do that, but we need to be careful. When I say (in my previous reply)
>>>> the ordering does not matter, that saying is from the UFS PHY HPG doc.
>>>> However, in SW implementation, the 'tbls_hs_b' is actually overwriting one
>>>> COM_VCO_TUNE_MAP register, the same register is also programmed by common
>>>> table or overlay table. So qmp_ufs_serdes_init(qmp, &cfg->tbls_hs_b) should
>>>> come after overlays.
>>>>
>>>
>>> Then you can program tbls_hs_b after overlay tables. Wouldn't that work?
>>
>> I am programming tbls_hs_b after overlay tables, just a heads up in case you
>> are surprised :).
>>
>
> Cool!
>
> - Mani
>