linux-kernel - Re: [RESEND PATCH v3 1/2] drivers: amba: Updates to component identification for driver matching.

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Message-ID: <353c8f4b-f48f-863c-7149-342b764a02c0@codeaurora.org>
Date:   Fri, 25 Jan 2019 12:50:49 +0530
From:   Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
To:     Mike Leach <mike.leach@...aro.org>, linux@...linux.org.uk
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        coresight@...ts.linaro.org, linux-kernel@...r.kernel.org,
        mathieu.poirier@...aro.org,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Rajendra Nayak <rnayak@...eaurora.org>,
        Vivek Gautam <vivek.gautam@...eaurora.org>,
        Sibi Sankar <sibis@...eaurora.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
Subject: Re: [RESEND PATCH v3 1/2] drivers: amba: Updates to component
 identification for driver matching.

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.

With this,

Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>

Thanks,
Sai

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