linux-kernel - Re: [PATCH v2 6/6] pinctrl: intel: Enumerate PWM device when community has a capabilitty

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Date:   Thu, 10 Nov 2022 08:44:56 +0100
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        Thierry Reding <thierry.reding@...il.com>,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-pwm@...r.kernel.org, Andy Shevchenko <andy@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>
Subject: Re: [PATCH v2 6/6] pinctrl: intel: Enumerate PWM device when
 community has a capabilitty

On Tue, Nov 08, 2022 at 04:22:26PM +0200, Andy Shevchenko wrote:
> Some of the Communities may have PWM capability. In such cases,
> enumerate PWM device via respective driver. User is still responsible
> for setting correct pin muxing for the line that needs to output the
> signal.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Reviewed-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> ---
>  drivers/pinctrl/intel/pinctrl-intel.c | 29 +++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/pinctrl/intel/pinctrl-intel.c b/drivers/pinctrl/intel/pinctrl-intel.c
> index 6e630e87fed6..6b685ff7041f 100644
> --- a/drivers/pinctrl/intel/pinctrl-intel.c
> +++ b/drivers/pinctrl/intel/pinctrl-intel.c
> @@ -24,6 +24,8 @@
>  #include <linux/pinctrl/pinctrl.h>
>  #include <linux/pinctrl/pinmux.h>
>  
> +#include <linux/platform_data/x86/pwm-lpss.h>
> +
>  #include "../core.h"
>  #include "pinctrl-intel.h"
>  
> @@ -49,6 +51,8 @@
>  #define PADOWN_MASK(p)			(GENMASK(3, 0) << PADOWN_SHIFT(p))
>  #define PADOWN_GPP(p)			((p) / 8)
>  
> +#define PWMC				0x204
> +
>  /* Offset from pad_regs */
>  #define PADCFG0				0x000
>  #define PADCFG0_RXEVCFG_SHIFT		25
> @@ -1502,6 +1506,27 @@ static int intel_pinctrl_pm_init(struct intel_pinctrl *pctrl)
>  	return 0;
>  }
>  
> +static int intel_pinctrl_probe_pwm(struct intel_pinctrl *pctrl,
> +				   struct intel_community *community)
> +{
> +	static const struct pwm_lpss_boardinfo info = {
> +		.clk_rate = 19200000,
> +		.npwm = 1,
> +		.base_unit_bits = 22,
> +		.bypass = true,
> +	};
> +	struct pwm_lpss_chip *pwm;
> +
> +	if (!(community->features & PINCTRL_FEATURE_PWM))
> +		return 0;
> +
> +	pwm = pwm_lpss_probe(pctrl->dev, community->regs + PWMC, &info);
> +	if (IS_ERR(pwm) && PTR_ERR(pwm) != -ENODEV)
> +		return PTR_ERR(pwm);

Linus and Andy already agreed that this patch is ugly. I wonder if this
here would be a bit less ugly if you do:

	if (IS_REACHABLE(...)) {
		pwm = pwm_lpss_probe(...);
		...


	}

and drop the check PTR_ERR(pwm) != -ENODEV (which might have a different
semantic than "the pwm driver isn't available").

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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