Re: [PATCH 2/5] soundwire: qcom: add support for mmio soundwire devices

[Jonathan Marek <jonathan@marek.ca>]

On 6/9/20 5:18 AM, Srinivas Kandagatla wrote:
> 
> 
> On 09/06/2020 05:34, Vinod Koul wrote:
>> Hi Jonathan,
>>
>> On 08-06-20, 16:43, Jonathan Marek wrote:
>>> Adds support for qcom soundwire devices with memory mapped IO registers.
>>
>> Please use 'SoundWire Master devices' instead :)
>>
>>>
>>> Signed-off-by: Jonathan Marek <jonathan@marek.ca>
>>> ---
>>>   drivers/soundwire/qcom.c | 25 +++++++++++++++++++++++--
>>>   1 file changed, 23 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/soundwire/qcom.c b/drivers/soundwire/qcom.c
>>> index f38d1fd3679f..628747df1c75 100644
>>> --- a/drivers/soundwire/qcom.c
>>> +++ b/drivers/soundwire/qcom.c
>>> @@ -90,6 +90,7 @@ struct qcom_swrm_ctrl {
>>>       struct sdw_bus bus;
>>>       struct device *dev;
>>>       struct regmap *regmap;
>>> +    void __iomem *mmio;
>>>       struct completion *comp;
>>>       struct work_struct slave_work;
>>>       /* read/write lock */
>>> @@ -154,6 +155,20 @@ static int qcom_swrm_ahb_reg_write(struct 
>>> qcom_swrm_ctrl *ctrl,
>>>       return SDW_CMD_OK;
>>>   }
>>> +static int qcom_swrm_cpu_reg_read(struct qcom_swrm_ctrl *ctrl, int reg,
>>> +                  u32 *val)
>>> +{
>>> +    *val = readl(ctrl->mmio + reg);
>>> +    return SDW_CMD_OK;
>>> +}
>>> +
>>> +static int qcom_swrm_cpu_reg_write(struct qcom_swrm_ctrl *ctrl, int 
>>> reg,
>>> +                   int val)
>>> +{
>>> +    writel(val, ctrl->mmio + reg);
>>> +    return SDW_CMD_OK;
>>> +}
>>
>> this looks fine but regmap supports mmio also, so I am thinking we
>> should remove these and set regmap (mmio/slim)... Srini..?
> 
> That is doable, but not going to add great value in this case, unless we 
> are having another layer of abstraction. So keeping it as readl/writel 
> seems okay to me.
> 

Adding to this, the slim case doesn't use the regmap directly, it goes 
through AHB_BRIDGE registers. So using a single regmap path is not 
"doable" (at least not in a nice way IMO).

> --srini
> 
> 
>>