From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Sverdlin Subject: Re: [PATCH] i2c: davinci: Fix bus rate calculation on Keystone SoC Date: Thu, 13 Aug 2015 12:29:06 +0200 Message-ID: <55CC7172.9090700@nokia.com> References: <5582870B.7030304@nokia.com> <558288B0.1020706@ti.com> <5582F049.8070407@ti.com> <20150709195309.GI4744@katana> <559FEC8C.9030603@ti.com> <55A00E56.2020308@ti.com> <20150812084352.GA1524@katana> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150812084352.GA1524@katana> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: ext Wolfram Sang , Grygorii Strashko Cc: Sekhar Nori , Murali Karicheri , Kevin Hilman , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org Hello Wolfram, On 12/08/15 10:43, ext Wolfram Sang wrote: >> > My opinion - it's time for compatible string :) "ti,keystone-i2c". >> > Especially taking int account two things: >> > 1) In Datasheet SPRS893B TCI6630K2L Multicore DSP+ARM KeyStone II System-on-Chip (SoC) (Rev. E) >> > values for those registers specified as: >> > 0x0034 ICPID1 I2C Peripheral Identification Register 1 [value: 0x0000 0105] >> > 0x0038 ICPID2 I2C Peripheral Identification Register 2 [value: 0x0000 0005] >> > (actually the same is in k2h, k2e Datasheets). >> > >> > 2) This is not the first time such discussion has been raised. >> > >> > >>>>> > >> > This is not really critical fix. Currently bus rate is lower than expected because of these >>>>> > >> > calculation errors. The fix maximizes the bus rate. So newer SoCs will run little bit slower >>>>> > >> > until support is added to this part of the code. Not really critical. >> > >> > Regarding the patch itself: >> > - Seems the "d" value is fixed to 6 as per User Guide SPRUGV3 >> > "KeyStone Architecture 2 Inter-IC Control Bus (I2C)" and this change is correct. >> > It would be nice to have ref on document in commit message as above. >> > >> > - I think, it will be very useful to have same real digits/calculation mentioned in >> > commit message which can show how valuable is the improvement. > Alexander, any comments to this feedback? I would need to rework the patch to distinguish Keystones basing on DT compatible property. I will re-send another version along with actual bofore-after real world numbers. Thanks for feedback! -- Best regards, Alexander Sverdlin.