From: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
To: Mike Leach <mike.leach@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Stephen Boyd <swboyd@chromium.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-arm-msm@vger.kernel.org,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
Russell King <linux@armlinux.org.uk>
Subject: Re: [PATCH] coresight: dynamic-replicator: Fix handling of multiple connections
Date: Wed, 13 May 2020 21:03:41 +0530 [thread overview]
Message-ID: <5a76926a6532d3f91cca169d474ba98e@codeaurora.org> (raw)
In-Reply-To: <CAJ9a7VjAoUmMG9pLEzE_rMSpOjwVOi-ZCinF87n9H0JgfMDsiQ@mail.gmail.com>
Hi Mike,
On 2020-05-13 03:22, Mike Leach wrote:
[...]
>
> Looking at the AMBA driver there is a comment there that AMBA does not
> lose state when clocks are removed. This is consistent with the AMBA
> protocol spec which states that AMBA slaves can only be accessed /
> read / write on various strobe signals, or state reset on PRESET
> signal, all timed by the rising edge of the bus clock. state changes
> are not permitted on clock events alone. Given this static nature of
> AMBA slaves then removing the clock should not have any effect.
>
> The AMBA driver only /drivers/amba/bus.c gives permission to
> remove/restore the clocks from the devices (pm_suspend pm_resume
> callbacks) - this reduces the power consumption of these devices if
> the clock is not running, but state must be retained.
>
Thanks for the clarification.
>> >> >>
>> >> >> pid=0x2bb909 for both replicators. So part number is same.
>> >> >> UCI will be different for different implementation(QCOM maybe
>> >> >> different from ARM),
>> >> >> but will it be different for different replicators under the same
>> >> >> impl(i.e., on QCOM).
>> >> >
>> >> > May be use PIDR4.DES_2 to match the Implementor and apply the work
>> >> > around for all QCOM replicators ?
>> >> >
>> >> > To me that sounds the best option.
>> >> >
>> >>
>> >
>> > I agree, if it can be established that the register values that make
>> > up UCI (pid0-4, devarch, devtype, PID:CLASS==0x9), can correctly
>> > identify the parts then a flag can be set in the probe() function and
>> > acted on during the enable() function.
>> >
>>
>> So here I have a doubt as to why we need to use UCI because PID =
>> 0x2bb909
>> and CID = 0xb105900d are same for both replicators, so UCI won't
>> identify the
>> different replicators(in same implementation i.e., on QCOM) here.
>> Am I missing something?
>>
>> Thats why I think Suzuki suggested to use PIDR4_DES2 and check for
>> QCOM
>> impl
>> and add a workaround for all replicators, something like below: (will
>> need cleaning)
>>
>> #define PIDR4_DES2 0xFD0
>>
>> if (FIELD_GET(GENMASK(3, 0), readl_relaxed(drvdata->base +
>> PIDR4_DES2))
>> == 0x4)
>> id0val = id1val = 0xff;
>>
>
> Please look at the CoreSight components specification 3.0 (ARM IHI
> 0029E) Section B2.1.2 which describes the Unique Component Identifier
> (UCI).
> As mentioned above this consists of a combination of bits from
> multiple registers, including PIDR4.
>
Ok got it now, thanks for clearing the doubt. I will go ahead with
this method to identify QCOM impl and post a patch.
Thanks,
Sai
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member
of Code Aurora Forum, hosted by The Linux Foundation
next prev parent reply other threads:[~2020-05-13 15:34 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-26 14:37 [PATCH] coresight: dynamic-replicator: Fix handling of multiple connections Sai Prakash Ranjan
2020-04-27 9:20 ` Suzuki K Poulose
2020-04-27 9:45 ` Mike Leach
2020-04-27 13:53 ` Suzuki K Poulose
2020-04-28 12:23 ` Sai Prakash Ranjan
2020-04-29 11:47 ` Sai Prakash Ranjan
2020-04-29 13:49 ` Suzuki K Poulose
2020-04-29 13:59 ` Sai Prakash Ranjan
2020-04-29 14:27 ` Mike Leach
2020-04-29 14:48 ` Sai Prakash Ranjan
2020-04-29 16:58 ` Mike Leach
2020-04-29 17:11 ` Sai Prakash Ranjan
2020-05-06 7:35 ` Sai Prakash Ranjan
2020-05-08 8:53 ` Sai Prakash Ranjan
2020-05-11 11:14 ` Mike Leach
2020-05-11 14:16 ` Sai Prakash Ranjan
2020-05-11 14:30 ` Suzuki K Poulose
2020-05-11 14:41 ` Sai Prakash Ranjan
2020-05-12 11:49 ` Mike Leach
2020-05-12 17:45 ` Mathieu Poirier
2020-05-12 17:46 ` Sai Prakash Ranjan
2020-05-12 21:52 ` Mike Leach
2020-05-13 1:49 ` Stephen Boyd
2020-05-13 15:45 ` Sai Prakash Ranjan
2020-05-13 15:33 ` Sai Prakash Ranjan [this message]
2020-05-16 10:04 ` Sai Prakash Ranjan
2020-05-19 9:04 ` Sai Prakash Ranjan
2020-05-11 14:34 ` Sai Prakash Ranjan
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