linux-kernel - Re: [PATCH v2 01/16] drivers: pwm: core: use a single of xlate function

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Message-ID: <d657c681-da16-712d-0570-8c05c6bfd550@baylibre.com>
Date:   Tue, 16 Jan 2018 10:07:05 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Claudiu Beznea <claudiu.beznea@...rochip.com>,
        thierry.reding@...il.com, robh+dt@...nel.org, mark.rutland@....com,
        linux@...linux.org.uk, daniel@...que.org, haojian.zhuang@...il.com,
        robert.jarzmik@...e.fr, corbet@....net,
        nicolas.ferre@...rochip.com, alexandre.belloni@...e-electrons.com
Cc:     linux-pwm@...r.kernel.org, Mike Dunn <mikedunn@...sguy.com>,
        Alexander Shiyan <shc_work@...l.ru>,
        devicetree@...r.kernel.org,
        Brian Norris <briannorris@...omium.org>,
        linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        linux-rpi-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 01/16] drivers: pwm: core: use a single of xlate
 function

On 12/01/2018 15:22, Claudiu Beznea wrote:
> Remove of_pwm_simple_xlate() and of_pwm_xlate_with_flags() functions
> and add of_pwm_xlate() which is used in all cases no mather if the OF
> bindings are with PWM flags or not. This should not affect the old
> behavior since the xlate will be based on #pwm-cells property of the
> PWM controller. Based on #pwm-cells property the xlate will consider
> the flags or not. This will permit the addition of other inputs to OF
> xlate by just adding proper code at the end of of_pwm_xlate() and a new
> input to enum pwm_args_xlate_options. With this changes there will be
> no need to fill of_xlate and of_pwm_n_cells of struct pwm_chip from
> the drivers probe methods. References in drives to references to of_xlate
> and of_pwm_n_cells were removed. Drivers which used private of_xlate
> functions switched to the generic of_pwm_xlate() function which fits
> for it but with little changes in device trees (these drivers translated
> differently the "pwms" bindings; the "pwms" bindings now are generic to
> all drivers and all drivers should provide them in the format described
> in pwm documentation).
> 
> Cc: Thierry Reding <thierry.reding@...il.com>
> Cc: Mike Dunn <mikedunn@...sguy.com>
> Cc: Brian Norris <briannorris@...omium.org>
> Cc: Alexander Shiyan <shc_work@...l.ru>
> Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
> ---
> 
> This patch (and the next 7) could be applied independetly by this series, if
> any, but I choosed to have it here since it makes easy the PWM modes parsing.
> If you feel it could be independently of this series I could send a new version.
> 
> Also, Thierry, Mike, Brian, Shiyan, please take an extra look over pwm-pxa.c,
> pwm-cros-ec.c and pwm-clps711x.c since these were moved to use the generic
> pwms (minimum 2 pwm-cells).
> 
>  drivers/pwm/core.c             | 56 +++++++++++-------------------------------
>  drivers/pwm/pwm-atmel-hlcdc.c  |  2 --
>  drivers/pwm/pwm-atmel-tcb.c    |  2 --
>  drivers/pwm/pwm-atmel.c        |  6 -----
>  drivers/pwm/pwm-bcm-iproc.c    |  2 --
>  drivers/pwm/pwm-bcm-kona.c     |  2 --
>  drivers/pwm/pwm-bcm2835.c      |  2 --
>  drivers/pwm/pwm-berlin.c       |  2 --
>  drivers/pwm/pwm-clps711x.c     | 11 ---------
>  drivers/pwm/pwm-cros-ec.c      | 20 ---------------
>  drivers/pwm/pwm-fsl-ftm.c      |  2 --
>  drivers/pwm/pwm-hibvt.c        |  2 --
>  drivers/pwm/pwm-imx.c          |  8 ------
>  drivers/pwm/pwm-lpc18xx-sct.c  |  2 --
>  drivers/pwm/pwm-meson.c        |  2 --
>  drivers/pwm/pwm-omap-dmtimer.c |  2 --
>  drivers/pwm/pwm-pxa.c          | 19 --------------
>  drivers/pwm/pwm-renesas-tpu.c  |  2 --
>  drivers/pwm/pwm-rockchip.c     |  5 ----
>  drivers/pwm/pwm-samsung.c      |  3 ---
>  drivers/pwm/pwm-sun4i.c        |  2 --
>  drivers/pwm/pwm-tiecap.c       |  2 --
>  drivers/pwm/pwm-tiehrpwm.c     |  2 --
>  drivers/pwm/pwm-vt8500.c       |  2 --
>  drivers/pwm/pwm-zx.c           |  2 --
>  include/linux/pwm.h            | 23 ++++++++++-------
>  26 files changed, 29 insertions(+), 156 deletions(-)
> 

[...]
> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> index 0767deba8e62..6702fcc203ce 100644
> --- a/drivers/pwm/pwm-meson.c
> +++ b/drivers/pwm/pwm-meson.c
> @@ -535,8 +535,6 @@ static int meson_pwm_probe(struct platform_device *pdev)
>  	meson->chip.ops = &meson_pwm_ops;
>  	meson->chip.base = -1;
>  	meson->chip.npwm = 2;
> -	meson->chip.of_xlate = of_pwm_xlate_with_flags;
> -	meson->chip.of_pwm_n_cells = 3;
>  
>  	meson->data = of_device_get_match_data(&pdev->dev);
>  	meson->inverter_mask = BIT(meson->chip.npwm) - 1;
> diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c
> index 5ad42f33e70c..6bd32ae6dd3e 100644
> --- a/drivers/pwm/pwm-omap-dmtimer.c
> +++ b/drivers/pwm/pwm-omap-dmtimer.c
> @@ -317,8 +317,6 @@ static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
>  	omap->chip.ops = &pwm_omap_dmtimer_ops;
>  	omap->chip.base = -1;
>  	omap->chip.npwm = 1;
> -	omap->chip.of_xlate = of_pwm_xlate_with_flags;
> -	omap->chip.of_pwm_n_cells = 3;
>  
>  	mutex_init(&omap->mutex);
>  
[...]

Hi Claudiu,

Please avoid changing the device tree plumbing, this of_xlate fields are needed since
some platforms will need to have their own translate functions.

Moving a to single mandatory xlate function is going backward, a possible move
would be to default to of_pwm_xlate_with_flags and 3 cells if of_xlate is NULL,
or use the platforms xlate if provided.

Moving to a single xlate function is unrelated to your needs and can break some platforms.

Neil