linux-kernel - Re: [PATCH 08/12] coresight tmc: Handle configuration types properly

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Message-ID: <CANLsYkz_WLDNHS1jhZbfm7iUPt3kUhiMV1Ti0Aig30Un9evx=w@mail.gmail.com>
Date:   Thu, 15 Jun 2017 08:33:24 -0600
From:   Mathieu Poirier <mathieu.poirier@...aro.org>
To:     Suzuki K Poulose <Suzuki.Poulose@....com>
Cc:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 08/12] coresight tmc: Handle configuration types properly

On 15 June 2017 at 04:25, Suzuki K Poulose <Suzuki.Poulose@....com> wrote:
> On 14/06/17 18:59, Mathieu Poirier wrote:
>>
>> On Mon, Jun 12, 2017 at 03:36:47PM +0100, Suzuki K Poulose wrote:
>>>
>>> Coresight SoC 600 defines a new configuration for TMC, Embedded Trace
>>> Streamer (ETS), indicated by 0x3 in MODE:CONFIG_TYPE. Make sure
>>> the driver handles the new type properly.
>>
>>
>> From what I see below this patch only improves readability by moving the
>> if/else
>> compound to a case statement - there is no trace of the new ETS block.
>> Readability enhancement are good but the changelog must match the code.
>
>
> Mathieu,
>
> Not really. It fixes an issue with the current code. We check for ETB and
> ETR,
> if it doesn't match either of those, we assume it is ETF which is fine with
> SoC-400.
> But with SoC-600, we could have an ETS with id 0x3 and the driver could
> treat it
> as an ETF and go on with the initialisation. This patch makes sure that we
> do check for the ETF and report that ETS is not a supported configuration.

That is the description that should go in the changelog - it reflects
exactly what this patch is doing.

Mathieu.

>
> Suzuki
>
>>
>>>
>>> Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
>>> ---
>>>  drivers/hwtracing/coresight/coresight-tmc.c | 14 +++++++++++---
>>>  1 file changed, 11 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/hwtracing/coresight/coresight-tmc.c
>>> b/drivers/hwtracing/coresight/coresight-tmc.c
>>> index fd5a2e0..7152656 100644
>>> --- a/drivers/hwtracing/coresight/coresight-tmc.c
>>> +++ b/drivers/hwtracing/coresight/coresight-tmc.c
>>> @@ -358,11 +358,13 @@ static int tmc_probe(struct amba_device *adev,
>>> const struct amba_id *id)
>>>         desc.dev = dev;
>>>         desc.groups = coresight_tmc_groups;
>>>
>>> -       if (drvdata->config_type == TMC_CONFIG_TYPE_ETB) {
>>> +       switch (drvdata->config_type) {
>>> +       case TMC_CONFIG_TYPE_ETB:
>>>                 desc.type = CORESIGHT_DEV_TYPE_SINK;
>>>                 desc.subtype.sink_subtype =
>>> CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
>>>                 desc.ops = &tmc_etb_cs_ops;
>>> -       } else if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
>>> +               break;
>>> +       case TMC_CONFIG_TYPE_ETR:
>>>                 desc.type = CORESIGHT_DEV_TYPE_SINK;
>>>                 desc.subtype.sink_subtype =
>>> CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
>>>                 desc.ops = &tmc_etr_cs_ops;
>>> @@ -373,10 +375,16 @@ static int tmc_probe(struct amba_device *adev,
>>> const struct amba_id *id)
>>>                 ret = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(40));
>>>                 if (ret)
>>>                         goto out;
>>> -       } else {
>>> +               break;
>>> +       case TMC_CONFIG_TYPE_ETF:
>>>                 desc.type = CORESIGHT_DEV_TYPE_LINKSINK;
>>>                 desc.subtype.link_subtype =
>>> CORESIGHT_DEV_SUBTYPE_LINK_FIFO;
>>>                 desc.ops = &tmc_etf_cs_ops;
>>> +               break;
>>> +       default:
>>> +               pr_err("%s: Unsupported TMC config\n", pdata->name);
>>> +               ret = -EINVAL;
>>> +               goto out;
>>>         }
>>>
>>>         drvdata->csdev = coresight_register(&desc);
>>> --
>>> 2.7.4
>>>
>