linux-kernel - Re: [PATCH RFC 3/6] pwm: pwm-qti-lpg: Add PWM driver for QTI LPG module

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Message-ID: <20200728070801.evcfnq25a2f5d55r@pengutronix.de>
Date:   Tue, 28 Jul 2020 09:08:01 +0200
From:   Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
To:     Martin Botka <martin.botka1@...il.com>
Cc:     Fenglin Wu <fenglinw@...eaurora.org>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, Dan Murphy <dmurphy@...com>,
        Rob Herring <robh+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Lee Jones <lee.jones@...aro.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-pwm@...r.kernel.org
Subject: Re: [PATCH RFC 3/6] pwm: pwm-qti-lpg: Add PWM driver for QTI LPG
 module

Hello Martin,

On Mon, Jul 27, 2020 at 11:16:57PM +0200, Martin Botka wrote:
> Mo 27. 7. 2020 at 22:10 Uwe Kleine-König <u.kleine-koenig@...gutronix.de> wrote:
> >
> > On Fri, Jul 24, 2020 at 11:36:53PM +0200, Martin Botka wrote:
> > > From: Fenglin Wu <fenglinw@...eaurora.org>
> > >
> > > Add pwm_chip to support QTI LPG module and export LPG channels as
> > > PWM devices for consumer drivers' usage.
> > >
> > > Signed-off-by: Fenglin Wu <fenglinw@...eaurora.org>
> > > [martin.botka1@...il.com: Fast-forward the driver from kernel 4.14 to 5.8]
> > > Signed-off-by: Martin Botka <martin.botka1@...il.com>
> > > ---
> > >  drivers/pwm/Kconfig       |   10 +
> > >  drivers/pwm/Makefile      |    1 +
> > >  drivers/pwm/pwm-qti-lpg.c | 1284 +++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 1295 insertions(+)
> > >  create mode 100644 drivers/pwm/pwm-qti-lpg.c
> > >
> > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > > index cb8d739067d2..8a52d6884a9a 100644
> > > --- a/drivers/pwm/Kconfig
> > > +++ b/drivers/pwm/Kconfig
> > > @@ -399,6 +399,16 @@ config PWM_RCAR
> > >         To compile this driver as a module, choose M here: the module
> > >         will be called pwm-rcar.
> > >
> > > +config PWM_QTI_LPG
> > > +     tristate "Qualcomm Technologies, Inc. LPG driver"
> > > +     depends on  MFD_SPMI_PMIC && OF
> > > +     help
> > > +       This driver supports the LPG (Light Pulse Generator) module found in
> > > +       Qualcomm Technologies, Inc. PMIC chips. Each LPG channel can be
> > > +       configured to operate in PWM mode to output a fixed amplitude with
> > > +       variable duty cycle or in LUT (Look up table) mode to output PWM
> > > +       signal with a modulated amplitude.
> > > +
> > >  config PWM_RENESAS_TPU
> > >       tristate "Renesas TPU PWM support"
> > >       depends on ARCH_RENESAS || COMPILE_TEST
> > > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > > index a59c710e98c7..3555a6aa3f33 100644
> > > --- a/drivers/pwm/Makefile
> > > +++ b/drivers/pwm/Makefile
> > > @@ -37,6 +37,7 @@ obj-$(CONFIG_PWM_PCA9685)   += pwm-pca9685.o
> > >  obj-$(CONFIG_PWM_PUV3)               += pwm-puv3.o
> > >  obj-$(CONFIG_PWM_PXA)                += pwm-pxa.o
> > >  obj-$(CONFIG_PWM_RCAR)               += pwm-rcar.o
> > > +obj-$(CONFIG_PWM_QTI_LPG)    += pwm-qti-lpg.o
> >
> > Please keep this list alphabetically sorted.
> 
> OK
> 
> >
> > >  obj-$(CONFIG_PWM_RENESAS_TPU)        += pwm-renesas-tpu.o
> > >  obj-$(CONFIG_PWM_ROCKCHIP)   += pwm-rockchip.o
> > >  obj-$(CONFIG_PWM_SAMSUNG)    += pwm-samsung.o
> > > diff --git a/drivers/pwm/pwm-qti-lpg.c b/drivers/pwm/pwm-qti-lpg.c
> > > new file mode 100644
> > > index 000000000000..d24c3b3a3d8c
> > > --- /dev/null
> > > +++ b/drivers/pwm/pwm-qti-lpg.c
> > > @@ -0,0 +1,1284 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * Copyright (c) 2020, The Linux Foundation. All rights reserved.
> > > + */
> > > +
> > > +#define pr_fmt(fmt) "%s: " fmt, __func__
> >
> > This smells like debug stuff. Please drop this.
> 
> What do you mean ?
> The #define pr_fmt(fmt) or the tons of REG definitions ?

Either drop pr_fmt or at least don't have __func__ in it. This doesn't
belong into the kernel log (in the non-debug case at least).
(For debugging I like:

	#define pr_fmt(fmt) "%s:%d: " fmt, __func__, __LINE__

which helps finding the right printk line in the code from a given
output in functions with many printks.)

I don't mind the REG definitions, though aligning the values vertically
is common.

> > > +static const struct pwm_ops qpnp_lpg_pwm_ops = {
> > > +     .config = qpnp_lpg_pwm_config,
> > > +     .config_extend = qpnp_lpg_pwm_config_extend,
> > > +     .get_output_type_supported = qpnp_lpg_pwm_output_types_supported,
> > > +     .set_output_type = qpnp_lpg_pwm_set_output_type,
> > > +     .set_output_pattern = qpnp_lpg_pwm_set_output_pattern,
> > > +     .enable = qpnp_lpg_pwm_enable,
> > > +     .disable = qpnp_lpg_pwm_disable,
> >
> > As already noted in the former patch: Please implement .apply() and
> > .get_state().
> 
> So drop:
>     .get_output_type_supported = qpnp_lpg_pwm_output_types_supported,
>     .set_output_type = qpnp_lpg_pwm_set_output_type,
>     .set_output_pattern = qpnp_lpg_pwm_set_output_pattern,
> 
> Ad implement implement .apply and .get_state if i understood you correctly.
> Right ?

ack

Best regards
Uwe

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

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