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

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Date:   Thu, 15 Jun 2017 11:25:32 +0100
From:   Suzuki K Poulose <Suzuki.Poulose@....com>
To:     Mathieu Poirier <mathieu.poirier@...aro.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/12] coresight tmc: Handle configuration types properly

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.

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
>>