From: Wesley Terpstra <wesley@sifive.com>
To: Atish Patra <atish.patra@wdc.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
linux-pwm@vger.kernel.org, devicetree@vger.kernel.org,
linus.walleij@linaro.org, Palmer Dabbelt <palmer@sifive.com>,
linux-kernel@vger.kernel.org, Rob Herring <robh+dt@kernel.org>,
Christoph Hellwig <hch@infradead.org>,
linux-gpio@vger.kernel.org,
Thierry Reding <thierry.reding@gmail.com>,
linux-riscv@lists.infradead.org
Subject: Re: [RFC 1/4] pwm: sifive: Add DT documentation for SiFive PWM Controller.
Date: Mon, 15 Oct 2018 16:19:20 -0700 [thread overview]
Message-ID: <CAMgXwTieXNa13_xGp2mkw99+VJm-R1xrxMHSmRLZV-hG5oSdzA@mail.gmail.com> (raw)
Message-ID: <20181015231920.V_tmJvUmj0zmlZRdjBu96bIQ7VxZSCr_XHJWvtBcOBk@z> (raw)
In-Reply-To: <25758ab9-eb36-741b-6264-42412b3ddd8e@wdc.com>
On Mon, Oct 15, 2018 at 3:57 PM Atish Patra <atish.patra@wdc.com> wrote:
> >> +SiFive PWM controller
> >> +
> >> +Unlike most other PWM controllers, the SiFive PWM controller currently only
> >> +supports one period for all channels in the PWM. This is set globally in DTS.
> >> +The period also has significant restrictions on the values it can achieve,
> >> +which the driver rounds to the nearest achievable frequency.
> >
> > What restrictions are these? If "nearest achievable" is too far off the
> > target period it might be preferable to error out.
> >
>
> @Wes: Any comments?
When I last looked at this driver and hardware, I briefly considered
throwing up my hands and pretending that this PWM device had no period
control at all, only duty-cycle. There are several examples of PWM
controllers in linux already that behave that way.
Most of the uses of this PWM are only going to care about the
duty-cycle, not the period. So failing when the period is unachievable
seems worse to me than just completely eliminating access to period
control.
> I think yes. Since fu540 is the first Linux capable RISC-V core, SiFive
> Guys decided mark it as version 0.
>
> @Wesly: Please correct me if I am wrong.
Correct.
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2018-10-15 23:19 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-09 18:51 [RFC 0/4] GPIO & PWM support for HiFive Unleashed Atish Patra
2018-10-09 18:51 ` Atish Patra
2018-10-09 18:51 ` [RFC 1/4] pwm: sifive: Add DT documentation for SiFive PWM Controller Atish Patra
2018-10-09 18:51 ` Atish Patra
2018-10-10 13:49 ` Thierry Reding
2018-10-10 13:49 ` Thierry Reding
2018-10-15 22:57 ` Atish Patra
2018-10-15 22:57 ` Atish Patra
2018-10-15 23:19 ` Wesley Terpstra [this message]
2018-10-15 23:19 ` Wesley Terpstra
2018-10-16 11:13 ` Thierry Reding
2018-10-16 11:13 ` Thierry Reding
2018-10-16 11:01 ` Thierry Reding
2018-10-16 11:01 ` Thierry Reding
2018-10-16 17:31 ` Paul Walmsley
2018-10-16 17:31 ` Paul Walmsley
2018-10-16 22:04 ` Thierry Reding
2018-10-16 22:04 ` Thierry Reding
2018-10-16 22:20 ` Atish Patra
2018-10-16 22:20 ` Atish Patra
2018-10-17 15:58 ` Rob Herring
2018-10-17 15:58 ` Rob Herring
2018-10-17 21:45 ` Atish Patra
2018-10-17 21:45 ` Atish Patra
2018-11-10 5:38 ` Paul Walmsley
2018-11-10 5:38 ` Paul Walmsley
2018-10-10 13:51 ` Thierry Reding
2018-10-10 13:51 ` Thierry Reding
2018-10-15 22:45 ` Atish Patra
2018-10-15 22:45 ` Atish Patra
2018-10-16 10:51 ` Thierry Reding
2018-10-16 10:51 ` Thierry Reding
2018-10-16 22:42 ` Atish Patra
2018-10-16 22:42 ` Atish Patra
2018-10-09 18:51 ` [RFC 2/4] pwm: sifive: Add a driver for SiFive SoC PWM Atish Patra
2018-10-09 18:51 ` Atish Patra
2018-10-10 13:11 ` Christoph Hellwig
2018-10-10 13:11 ` Christoph Hellwig
2018-10-10 13:44 ` Thierry Reding
2018-10-10 13:44 ` Thierry Reding
2018-10-16 6:28 ` Atish Patra
2018-10-16 6:28 ` Atish Patra
2018-10-10 14:13 ` Thierry Reding
2018-10-10 14:13 ` Thierry Reding
2018-10-16 6:24 ` Atish Patra
2018-10-16 6:24 ` Atish Patra
2018-10-09 18:51 ` [RFC 3/4] gpio: sifive: Add DT documentation for SiFive GPIO Atish Patra
2018-10-09 18:51 ` Atish Patra
2018-10-09 18:51 ` [RFC 4/4] gpio: sifive: Add GPIO driver for SiFive SoCs Atish Patra
2018-10-09 18:51 ` Atish Patra
2018-10-10 12:35 ` Linus Walleij
2018-10-10 12:35 ` Linus Walleij
2018-10-17 1:01 ` Atish Patra
2018-10-17 1:01 ` Atish Patra
2019-09-18 7:32 ` Bin Meng
2018-10-10 13:01 ` Andreas Schwab
2018-10-10 13:01 ` Andreas Schwab
2018-10-10 13:12 ` Christoph Hellwig
2018-10-10 13:12 ` Christoph Hellwig
2018-10-10 13:28 ` Andreas Schwab
2018-10-10 13:28 ` Andreas Schwab
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAMgXwTieXNa13_xGp2mkw99+VJm-R1xrxMHSmRLZV-hG5oSdzA@mail.gmail.com \
--to=wesley@sifive.com \
--cc=atish.patra@wdc.com \
--cc=devicetree@vger.kernel.org \
--cc=hch@infradead.org \
--cc=linus.walleij@linaro.org \
--cc=linux-gpio@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=palmer@sifive.com \
--cc=robh+dt@kernel.org \
--cc=thierry.reding@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).