From: Qii Wang <qii.wang@mediatek.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: <matthias.bgg@gmail.com>, <linux-i2c@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>,
<linux-mediatek@lists.infradead.org>,
<srv_heupstream@mediatek.com>, <leilk.liu@mediatek.com>
Subject: Re: [RESEND] i2c: mediatek: Get device clock-stretch time via dts
Date: Wed, 14 Apr 2021 09:37:24 +0800 [thread overview]
Message-ID: <1618364244.32225.21.camel@mhfsdcap03> (raw)
In-Reply-To: <20210413201740.GC2751@kunai>
On Tue, 2021-04-13 at 22:17 +0200, Wolfram Sang wrote:
> On Mon, Apr 12, 2021 at 08:03:14PM +0800, Qii Wang wrote:
> > I can't see the relationship between "i2c-scl-falling-time-ns" and clock
> > stretching, is there a parameter related to clock stretching?
>
> ( you wrote "i2c-scl-falling-time-ns" above, didn't you mean
> "i2c-scl-internal-delay-ns" instead? )
>
I am sorry, I have confused your comment with lkjoon's comment in the
last mail. what I actually want to say is "i2c-scl-internal-delay-ns".
> Not yet, and I wonder if there can be one. In I2C (not SMBus), devices
> are allowed to stretch the clock as long as they want, so what should be
> specified here?
>
> I suggesteed "internal-delay" because AFAIU your hardware needs this
> delay to be able to cope with clock stretching.
>
If there is not a maximum value for clock stretching,
"i2c-scl-internal-delay-ns" should be a good choice for our hardware,
although it maybe not for clock stretching.
> > If you think both of them will affect the ac-timing of SCL, at this
> > point, "i2c-scl-falling-time-ns" maybe a good choice.
>
> Do you mean "i2c-scl-falling-time-ns" or "i2c-scl-internal-delay-ns"?
>
"i2c-scl-internal-delay-ns" is better.
Thanks for your review.
Qii
prev parent reply other threads:[~2021-04-14 1:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-13 8:04 [RESEND] i2c: mediatek: Get device clock-stretch time via dts qii.wang
2021-03-18 11:23 ` Wolfram Sang
2021-04-06 19:48 ` Wolfram Sang
2021-04-07 12:15 ` Qii Wang
2021-04-07 18:19 ` Wolfram Sang
2021-04-12 12:03 ` Qii Wang
2021-04-13 20:17 ` Wolfram Sang
2021-04-14 1:37 ` Qii Wang [this message]
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