Re: [PATCH 01/18] pwm: Provide devm_pwmchip_alloc() function

[Thierry Reding <thierry.reding@gmail.com>]

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On Tue, Jul 18, 2023 at 08:18:32PM +0200, Uwe Kleine-König wrote:
> This function allocates a struct pwm_chip and driver data. Compared to
> the status quo the split into pwm_chip and driver data is new, otherwise
> it doesn't change anything relevant (yet).
> 
> The intention is that after all drivers are switched to use this
> allocation function, its possible to add a struct device to struct
> pwm_chip to properly track the latter's lifetime without touching all
> drivers again. Proper lifetime tracking is a necessary precondition to
> introduce character device support for PWMs (that implements atomic
> setting and doesn't suffer from the sysfs overhead of the /sys/class/pwm
> userspace support).
> 
> The new function pwmchip_priv() (obviously?) only works for chips
> allocated with devm_pwmchip_alloc().

If this is supposed to be similar to the GPIO chardev, why doesn't GPIO
require this way of allocating a struct gpio_chip? I'm not a fan of
doing all this upfront work without seeing where this is ultimately
headed. Please hold off on reworking everything until you have a
complete proposal that can be reviewed in full.

Thierry

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