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SubjectRe: [RESEND PATCH v3 1/2] drivers: amba: Updates to component identification for driver matching.
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Mike,

On 25/01/2019 10:37, Mike Leach wrote:
> Hello Sai
> On Fri, 25 Jan 2019 at 07:20, Sai Prakash Ranjan
> <saiprakash.ranjan@codeaurora.org> wrote:
>>
>> Hi Mike,
>>
>> Thanks for the patch.
>>
>> BTW somehow I can't find the latest series in my inbox, so commenting
>> on this here.
>>
>> Mathieu pointed me to this patch series.This solves CPU debug module
>> sharing same PID as ETM on MSM8996. I will be posting patch for CPU
>> debug UCI table soon.
>>
>> But please find my one comment inline.
>>
>> On 12/19/2018 3:29 AM, Mike Leach wrote:
>>> The CoreSight specification (ARM IHI 0029E), updates the ID register
>>> requirements for components on an AMBA bus, to cover both traditional
>>> ARM Primecell type devices, and newer CoreSight and other components.
>>>
>>> The Peripheral ID (PID) / Component ID (CID) pair is extended in certain
>>> cases to uniquely identify components. CoreSight components related to
>>> a single function can share Peripheral ID values, and must be further
>>> identified using a Unique Component Identifier (UCI). e.g. the ETM, CTI,
>>> PMU and Debug hardware of the A35 all share the same PID.
>>>
>>
>> [..]
>>
>>> +static const struct amba_id *
>>> +amba_lookup(const struct amba_id *table, struct amba_device *dev)
>>> +{
>>> while (table->mask) {
>>> - ret = (dev->periphid & table->mask) == table->id;
>>> - if (ret)
>>> - break;
>>> + if (((dev->periphid & table->mask) == table->id) &&
>>> + ((dev->cid != CORESIGHT_CID) ||
>>> + (amba_cs_uci_id_match(table, dev))))
>>
>> Shouldn't the check be (dev->cid == CORESIGHT_CID) ?
>> Without this STM fails to probe on both SDM845 and MSM8996.
>>
> I believe the test is correct
>
> To expand the logic here:
>
> if (dev->periphid & table->mask) == table->id) {
> //** match on peripheral ID at this point
> if (CID != CORESIGHT_ID)
> return table; //** not coresight - match on peripheral ID only
> //** or
> if (amba_cs_uci_id_match() )
> return table; //** is coresight - match on UCI if
> available - otherwise peripheral ID only;
>
> However - looking at the coresight STM driver - this is using the
> private .data field in the amba_id for a name - which I had not
> spotted before.

Good point. We also use this field for Coresight SOC-600 ETR for
advertising the caps not detected from hardware.

> I will have to revisit this patchset to fix either the amba id struct
> or the method for getting the uci data into the amba_id.data which
> allows for multiple uses.

Thanks Mike !

Cheers
Suzuki

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