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, 7 Apr 2021 20:15:06 +0800 [thread overview]
Message-ID: <1617797706.32076.1.camel@mhfsdcap03> (raw)
In-Reply-To: <20210406194856.GF3122@kunai>
On Tue, 2021-04-06 at 21:48 +0200, Wolfram Sang wrote:
> On Sat, Mar 13, 2021 at 04:04:24PM +0800, qii.wang@mediatek.com wrote:
> > From: Qii Wang <qii.wang@mediatek.com>
> >
> > tSU,STA/tHD,STA/tSU,STOP maybe out of spec due to device
> > clock-stretching or circuit loss, we could get device
> > clock-stretch time from dts to adjust these parameters
> > to meet the spec via EXT_CONF register.
> >
> > Signed-off-by: Qii Wang <qii.wang@mediatek.com>
>
> I tried to understand from the code what the new binding expresses, but
> I don't fully understand it. Is it the maximum clock stretch time?
> Because I cannot recall a device which always uses the same delay for
> clock stretching.
>
Due to clock stretch, our HW IP cannot meet the ac-timing
spec(tSU;STA,tSU;STO).
There isn't a same delay for clock stretching, so we need pass a
parameter which can be found through measurement to meet most
conditions.
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next prev parent reply other threads:[~2021-04-07 12:17 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 [this message]
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
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