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Wed, 14 Apr 2021 09:37:26 +0800 Received: from [10.17.3.153] (10.17.3.153) by MTKCAS32.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 14 Apr 2021 09:37:25 +0800 Message-ID: <1618364244.32225.21.camel@mhfsdcap03> Subject: Re: [RESEND] i2c: mediatek: Get device clock-stretch time via dts From: Qii Wang To: Wolfram Sang CC: , , , , , , Date: Wed, 14 Apr 2021 09:37:24 +0800 In-Reply-To: <20210413201740.GC2751@kunai> References: <1615622664-15032-1-git-send-email-qii.wang@mediatek.com> <20210406194856.GF3122@kunai> <1617797706.32076.1.camel@mhfsdcap03> <20210407181936.GA1614@kunai> <1618228994.32225.3.camel@mhfsdcap03> <20210413201740.GC2751@kunai> X-Mailer: Evolution 3.10.4-0ubuntu2 MIME-Version: 1.0 X-TM-SNTS-SMTP: BDCD7573E06B32ECD29F8904F8F2797A0FA403DEDB2F512640FACE4A5C84AC0A2000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210413_184213_299725_D082BD36 X-CRM114-Status: GOOD ( 17.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel