linux-kernel - Re: [PATCH 4/5] soundwire: qcom: avoid dependency on CONFIG

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Message-ID: <dc8f59c6-2fa9-f3a3-6d77-2d03a6d2776b@marek.ca>
Date:   Tue, 9 Jun 2020 07:33:11 -0400
From:   Jonathan Marek <jonathan@...ek.ca>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        alsa-devel@...a-project.org
Cc:     Vinod Koul <vkoul@...nel.org>,
        Sanyog Kale <sanyog.r.kale@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:ARM/QUALCOMM SUPPORT" <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH 4/5] soundwire: qcom: avoid dependency on CONFIG_SLIMBUS

On 6/9/20 5:52 AM, Srinivas Kandagatla wrote:
> 
> 
> On 08/06/2020 21:43, Jonathan Marek wrote:
>> The driver may be used without slimbus, so don't depend on slimbus.
>>
>> Signed-off-by: Jonathan Marek <jonathan@...ek.ca>
>> ---
>>   drivers/soundwire/Kconfig | 1 -
>>   drivers/soundwire/qcom.c  | 5 +++++
>>   2 files changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/soundwire/Kconfig b/drivers/soundwire/Kconfig
>> index fa2b4ab92ed9..d121cf739090 100644
>> --- a/drivers/soundwire/Kconfig
>> +++ b/drivers/soundwire/Kconfig
>> @@ -33,7 +33,6 @@ config SOUNDWIRE_INTEL
>>   config SOUNDWIRE_QCOM
>>       tristate "Qualcomm SoundWire Master driver"
>> -    depends on SLIMBUS
>>       depends on SND_SOC
> 
> Why not move this to imply SLIMBUS this will give more flexibility!
> 
> 

If you mean to change it to "select SLIMBUS", I'd prefer not to, because 
this would increase code size unnecessarily in my kernel.

>>       help
>>         SoundWire Qualcomm Master driver.
>> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
>> index 14334442615f..ac81c64768ea 100644
>> --- a/drivers/soundwire/qcom.c
>> +++ b/drivers/soundwire/qcom.c
>> @@ -769,13 +769,18 @@ static int qcom_swrm_probe(struct 
>> platform_device *pdev)
>>       if (!ctrl)
>>           return -ENOMEM;
>> +#ifdef CONFIG_SLIMBUS
>>       if (dev->parent->bus == &slimbus_bus) {
>> +#else
>> +    if (false) {
>> +#endif
> 
> May be you can do bit more cleanup here, which could endup like:
> 
> 
> ctrl->regmap = dev_get_regmap(dev->parent, NULL);
> if (!ctrl->regmap) {
>      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>      if (res) {
>          ctrl->mmio = devm_ioremap_resource(dev, res);
>          if (IS_ERR(ctrl->mmio)) {
>              dev_err(dev, "No valid mem resource found\n");
>              return PTR_ERR(ctrl->mmio);
>          }
> 
>          ctrl->reg_read = qcom_swrm_cpu_reg_read;
>          ctrl->reg_write = qcom_swrm_cpu_reg_write;
>      } else {
>          dev_err(dev, "No valid slim resource found\n");
>          return -EINVAL;
>      }
> } else {
>      ctrl->reg_read = qcom_swrm_ahb_reg_read;
>      ctrl->reg_write = qcom_swrm_ahb_reg_write;
> }
> 
> 
> 
> thanks,
> srini

I don't think this is better, it feels more obfuscated, and I think its 
possible we may end up with the mmio sdw having a parent with a regmap. 
(it is not how I did things up in my upstream stack, but in downstream 
the sdw nodes are inside the "macro" codec nodes)

I understand the '#ifdef CONFIG_SLIMBUS'/'dev->parent->bus == 
&slimbus_bus' is ugly, but at least its clear what's going on. Unless 
you have a better suggestion?

>>           ctrl->reg_read = qcom_swrm_ahb_reg_read;
>>           ctrl->reg_write = qcom_swrm_ahb_reg_write;
>>           ctrl->regmap = dev_get_regmap(dev->parent, NULL);
>>           if (!ctrl->regmap)
>>               return -EINVAL;
>>       } else {
>> +
>>           res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>           ctrl->reg_read = qcom_swrm_cpu_reg_read;
>>