linux-kernel - Re: [PATCH v13 1/4] drivers pps/generators: replace copy of pps-gen info struct with const pointer

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Message-ID: <Z6mXC7loE3qRYpUQ@smile.fi.intel.com>
Date: Mon, 10 Feb 2025 08:04:59 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: subramanian.mohan@...el.com
Cc: linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	gregkh@...uxfoundation.org, giometti@...eenne.com,
	tglx@...utronix.de, corbet@....net, eddie.dong@...el.com,
	christopher.s.hall@...el.com, pandith.n@...el.com,
	thejesh.reddy.t.r@...el.com, david.zage@...el.com,
	srinivasan.chinnadurai@...el.com
Subject: Re: [PATCH v13 1/4] drivers pps/generators: replace copy of pps-gen
 info struct with const pointer

On Mon, Feb 10, 2025 at 10:34:18AM +0530, subramanian.mohan@...el.com wrote:
> From: Subramanian Mohan <subramanian.mohan@...el.com>
> 
> Some PPS generator drivers may need to retrieve a pointer to their
> internal data while executing the PPS generator enable() method.
> 
> During the driver registration the pps_gen_device pointer is returned
> from the framework, and for that reason, there is difficulty in
> getting generator driver data back in the enable function. We won't be
> able to use container_of macro as it results in static assert, and we
> might end up in using static pointer.
> 
> To solve the issue and to get back the generator driver data back, we
> should not copy the struct pps_gen_source_info within the struct
> pps_gen_device during the registration stage, but simply save the
> pointer of the driver one. In this manner, driver may get a pointer
> to their internal data as shown below:
> 
> struct pps_gen_foo_data_s {
>         ...
> 	struct pps_gen_source_info gen_info;
> 	struct pps_gen_device *pps_gen;
> 	...
> };
> 
> static int __init pps_gen_foo_init(void)
> {
>         struct pps_gen_foo_data_s *foo;
> 	...
> 
>         foo->pps_gen = pps_gen_register_source(&foo->gen_info);
> 	...
> }
> 
> Then, in the enable() method, we can retrieve the pointer to the main
> struct by using the code below:
> 
> static int pps_gen_foo_enable(struct pps_gen_device *pps_gen, bool enable)
> {
>         struct pps_gen_foo_data_s *foo = container_of(pps_gen->info,

> 	       			      struct pps_gen_foo_data_s, gen_info);

TABs/spaces mix.

>         ...
> }

> Signed-off-by: Rodolfo Giometti <giometti@...eenne.com>

Hmm... Is Rodolfo indeed a correct to be mentioned here?
I think you wanted Suggested-by with somebody else.

...

> -struct pps_gen_device *pps_gen_register_source(struct pps_gen_source_info *info)
> +struct pps_gen_device *pps_gen_register_source(
> +					const struct pps_gen_source_info *info)

Still leave it a single line.

...

Otherwise looks good to me, thanks for taking this approach!

-- 
With Best Regards,
Andy Shevchenko