Re: [PATCH] drm/bridge: ti-sn65dsi86: Implement the pwm_chip

From: Shawn Guo <shawn.guo@linaro.org>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	Thierry Reding <thierry.reding@gmail.com>,
	Lee Jones <lee.jones@linaro.org>,
	Doug Anderson <dianders@chromium.org>,
	linux-arm-msm <linux-arm-msm@vger.kernel.org>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-pwm@vger.kernel.org
Subject: Re: [PATCH] drm/bridge: ti-sn65dsi86: Implement the pwm_chip
Date: Thu, 10 Dec 2020 22:40:36 +0800	[thread overview]
Message-ID: <CAAQ0ZWQEhitxNCKBjTNGcv5E+yqwjfbb5GCLoctpJM7u4Zpp=A@mail.gmail.com> (raw)
In-Reply-To: <20201210130453.regjkemfneqbelsi@pengutronix.de>

Hi Uwe,

On Thu, Dec 10, 2020 at 9:05 PM Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
> > > @@ -111,6 +118,8 @@
> > >
> > >  #define SN_LINK_TRAINING_TRIES             10
> > >
> > > +#define SN_PWM_GPIO                        3
> >
> > So this maps to the GPIO4 described in sn65dsi86 datasheet.  I'm
> > wondering if it's more readable to define the following SHIFT constants
> > (your code), and use GPIO_MUX_GPIO4_SHIFT >> 2 where you need GPIO
> > offset?
> >
> > #define  GPIO_MUX_GPIO1_SHIFT 0
> > #define  GPIO_MUX_GPIO2_SHIFT 2
> > #define  GPIO_MUX_GPIO3_SHIFT 4
> > #define  GPIO_MUX_GPIO4_SHIFT 6
> >
> > If you agree, you may consider to integrate this patch beforehand:
> >
> > https://github.com/shawnguo2/linux/commit/7cde887ffb3b27a36e77a08bee3666d14968b586
>
> My preferred way here would be to add a prefix for the other constants.
> It (IMHO) looks nicer and
>
>         GPIO_INPUT_SHIFT
>
> looks like a quite generic name for a hardware specific definition.

While this looks like a reasonable argument, I also like the naming
choice for these constants in the beginning for that distinction
between registers and bits.  And changing the names the other way
around means there will be a much bigger diffstat, which I would like
to avoid.  I suggest let's just focus on what really matters here -
keep the naming consistent, so that people do not get confused when
they want to add more constants in there.

Shawn

> (Even if up to now there is no other code location using this name.)