netdev - Re: [EXTERNAL] Re: [EXTERNAL] Re: [PATCH v3 3/6] soc: ti: pruss: Add pruss_cfg

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Date:   Fri, 10 Mar 2023 15:23:34 +0200
From:   Roger Quadros <rogerq@...nel.org>
To:     Md Danish Anwar <a0501179@...com>,
        MD Danish Anwar <danishanwar@...com>,
        "Andrew F. Davis" <afd@...com>, Suman Anna <s-anna@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Nishanth Menon <nm@...com>
Cc:     linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, srk@...com, devicetree@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [EXTERNAL] Re: [EXTERNAL] Re: [PATCH v3 3/6] soc: ti: pruss: Add
 pruss_cfg_read()/update() API

Hi Danish,

On 10/03/2023 13:53, Md Danish Anwar wrote:
> Hi Roger,
> 
> On 09/03/23 17:00, Md Danish Anwar wrote:
>> Hi Roger,
>>
>> On 08/03/23 17:12, Roger Quadros wrote:
>>>
>>>
>>> On 08/03/2023 13:36, Md Danish Anwar wrote:
>>>> Hi Roger,
>>>>
>>>> On 08/03/23 13:57, Roger Quadros wrote:
>>>>> Hi,
>>>>>
>>>>> On 06/03/2023 13:09, MD Danish Anwar wrote:
>>>>>> From: Suman Anna <s-anna@...com>
>>>>>>
>>>>>> Add two new generic API pruss_cfg_read() and pruss_cfg_update() to
>>>>>> the PRUSS platform driver to allow other drivers to read and program
>>>>>> respectively a register within the PRUSS CFG sub-module represented
>>>>>> by a syscon driver. This interface provides a simple way for client
>>>>>
>>>>> Do you really need these 2 functions to be public?
>>>>> I see that later patches (4-6) add APIs for doing specific things
>>>>> and that should be sufficient than exposing entire CFG space via
>>>>> pruss_cfg_read/update().
>>>>>
>>>>>
>>>>
>>>> I think the intention here is to keep this APIs pruss_cfg_read() and
>>>> pruss_cfg_update() public so that other drivers can read / modify PRUSS config
>>>> when needed.
>>>
>>> Where are these other drivers? If they don't exist then let's not make provision
>>> for it now.
>>> We can provide necessary API helpers when needed instead of letting client drivers
>>> do what they want as they can be misused and hard to debug.
>>>
>>
>> The ICSSG Ethernet driver uses pruss_cfg_update() API. It is posted upstream in
>> the series [1]. The ethernet driver series is dependent on this series. In
>> series [1] we are using pruss_cfg_update() in icssg_config.c file,
>> icssg_config() API.

You can instead add a new API on what exactly you want it to do rather than exposing
entire CFG space.

>>
>> So for this, the API pruss_cfg_update() needs to be public.
>>
>> [1] https://lore.kernel.org/all/20230210114957.2667963-3-danishanwar@ti.com/
>>
> 
> I will keep this patch as it is as pruss_cfg_update() needs to be public for
> ICSSG Ethernet driver and pruss_cfg_read() is kind of a complementary function
> to update. I will do required changes in other patches and send next revision
> if that's OK with you. Please let me know.
> 
>>>>
>>>> The later patches (4-6) add APIs to do specific thing, but those APIs also
>>>> eventually call pruss_cfg_read/update().
>>>
>>> They can still call them but they need to be private to pruss.c
>>>
>>>>
>>>>>> drivers without having them to include and parse the CFG syscon node
>>>>>> within their respective device nodes. Various useful registers and
>>>>>> macros for certain register bit-fields and their values have also
>>>>>> been added.
>>>>>>
>>>>>> It is the responsibility of the client drivers to reconfigure or
>>>>>> reset a particular register upon any failures.
>>>>>>
>>>>>> Signed-off-by: Suman Anna <s-anna@...com>
>>>>>> Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
>>>>>> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
>>>>>> Signed-off-by: Puranjay Mohan <p-mohan@...com>
>>>>>> ---
>>>>>>  drivers/soc/ti/pruss.c           |  41 +++++++++++++
>>>>>>  include/linux/remoteproc/pruss.h | 102 +++++++++++++++++++++++++++++++
>>>>>>  2 files changed, 143 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/soc/ti/pruss.c b/drivers/soc/ti/pruss.c
>>>>>> index c8053c0d735f..537a3910ffd8 100644
>>>>>> --- a/drivers/soc/ti/pruss.c
>>>>>> +++ b/drivers/soc/ti/pruss.c
>>>>>> @@ -164,6 +164,47 @@ int pruss_release_mem_region(struct pruss *pruss,
>>>>>>  }
>>>>>>  EXPORT_SYMBOL_GPL(pruss_release_mem_region);
>>>>>

cheers,
-roger