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From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>
Cc: "linux-renesas-soc@vger.kernel.org" 
	<linux-renesas-soc@vger.kernel.org>,
	"linux-pwm@vger.kernel.org" <linux-pwm@vger.kernel.org>,
	"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>
Subject: RE: [PATCH 5/5] pwm: rcar: add workaround to output "pseudo" low level
Date: Wed, 12 Dec 2018 10:49:32 +0000	[thread overview]
Message-ID: <OSBPR01MB2293ACA05221DB5A6D3A6BB2D8A70@OSBPR01MB2293.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <20181212073733.th23v5cvaxfbhy53@pengutronix.de>

Hi Uwe,

> From: Uwe Kleine-König, Sent: Wednesday, December 12, 2018 4:38 PM
<snip>
> > > In the past I suggested to weaken the requirements after pwm_disable,
> > > but Thierry didn't like it.
> >
> > I read the following discussion once:
> > https://patchwork.ozlabs.org/patch/959776/
> 
> Yeah, that's (part of) the discussion I meant. Thierry doesn't agree
> though, so for now that's a dead end. My plan is to watch the pwm list
> for a while to get a better picture about the different pwm
> implementations because just one or two problematic cases are not
> enough to justify a generic solution in the core in his eyes.

I got it.

> > I could not understand all this yet, but I think I should try to add a special gpio handling
> > to the pwm-rcar.c driver instead of a generic approach because as you mentioned above,
> > such special handling needs for the hardware.
> 
> Being able to set PHO to zero would be still better, so I hope you
> follow up on the question to your hardware guys if this is really
> forbidden. (If I had access to such hardware, I'd bluntly try what
> happens.)

The hardware guy said that the output level is always high if PH0 is set to 0.
However, the PH0 bitfields means "PWM High-Level Period" so that the behavior of
the zero differs between the document and the hardware. So, we have to assume
this is really forbidden unfortunately...

Best regards,
Yoshihiro Shimoda

> Best regards
> Uwe
> 
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |

  reply	other threads:[~2018-12-12 10:49 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-07  8:29 [PATCH 0/5] pwm: rcar: Add support "atomic" API and workaround Yoshihiro Shimoda
2018-12-07  8:29 ` [PATCH 1/5] pwm: rcar: add rcar_pwm_calc_counter() to calculate PWMCNT value only Yoshihiro Shimoda
2018-12-07  9:00   ` Uwe Kleine-König
2018-12-07  9:00     ` Uwe Kleine-König
2018-12-07  8:29 ` [PATCH 2/5] pwm: rcar: Add support "atomic" API Yoshihiro Shimoda
2018-12-07  9:07   ` Uwe Kleine-König
2018-12-07  9:07     ` Uwe Kleine-König
2018-12-07  9:57     ` Geert Uytterhoeven
2018-12-07 10:45       ` Uwe Kleine-König
2018-12-07 10:45         ` Uwe Kleine-König
2018-12-10  4:58         ` Yoshihiro Shimoda
2018-12-07  8:29 ` [PATCH 3/5] pwm: rcar: Use "atomic" API on rcar_pwm_resume() Yoshihiro Shimoda
2018-12-07  8:29 ` [PATCH 4/5] pwm: rcar: remove legacy APIs Yoshihiro Shimoda
2018-12-07  8:29 ` [PATCH 5/5] pwm: rcar: add workaround to output "pseudo" low level Yoshihiro Shimoda
2018-12-07  9:13   ` Uwe Kleine-König
2018-12-07  9:13     ` Uwe Kleine-König
2018-12-10  4:49     ` Yoshihiro Shimoda
2018-12-10  8:11       ` Uwe Kleine-König
2018-12-10  8:11         ` Uwe Kleine-König
2018-12-12  3:19         ` Yoshihiro Shimoda
2018-12-12  3:19           ` Yoshihiro Shimoda
2018-12-12  7:37           ` Uwe Kleine-König
2018-12-12  7:37             ` Uwe Kleine-König
2018-12-12 10:49             ` Yoshihiro Shimoda [this message]
2018-12-12 10:49               ` Yoshihiro Shimoda
2018-12-13  9:47     ` Yoshihiro Shimoda
2018-12-13  9:47       ` Yoshihiro Shimoda
2018-12-13  9:52       ` Uwe Kleine-König
2018-12-13  9:52         ` Uwe Kleine-König
2018-12-13 10:53         ` Yoshihiro Shimoda
2018-12-13 10:53           ` Yoshihiro Shimoda
2018-12-07 21:49 ` pwm: rcar: improve calculation of divider Uwe Kleine-König
2018-12-07 21:49   ` Uwe Kleine-König
2018-12-09 20:55   ` Laurent Pinchart
2018-12-10  5:09     ` Yoshihiro Shimoda
2018-12-10  8:04       ` Uwe Kleine-König
2018-12-10  8:04         ` Uwe Kleine-König
2018-12-12  3:13         ` Yoshihiro Shimoda
2018-12-12  3:13           ` Yoshihiro Shimoda
2018-12-09 22:48 ` [PATCH 0/5] pwm: rcar: Add support "atomic" API and workaround Laurent Pinchart

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