From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH] i2c: davinci: Fix bus rate calculation on Keystone SoC Date: Wed, 12 Aug 2015 10:43:52 +0200 Message-ID: <20150812084352.GA1524@katana> References: <5582870B.7030304@nokia.com> <558288B0.1020706@ti.com> <5582F049.8070407@ti.com> <20150709195309.GI4744@katana> <559FEC8C.9030603@ti.com> <55A00E56.2020308@ti.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="SUOF0GtieIMvvwua" Return-path: Content-Disposition: inline In-Reply-To: <55A00E56.2020308-l0cyMroinI0@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Grygorii Strashko Cc: Sekhar Nori , Murali Karicheri , Alexander Sverdlin , Kevin Hilman , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org --SUOF0GtieIMvvwua Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jul 10, 2015 at 09:26:30PM +0300, Grygorii Strashko wrote: > Hi, > On 07/10/2015 07:02 PM, Sekhar Nori wrote: > > On Friday 10 July 2015 01:23 AM, Wolfram Sang wrote: > >> On Thu, Jun 18, 2015 at 12:22:33PM -0400, Murali Karicheri wrote: > >>> On 06/18/2015 05:00 AM, Sekhar Nori wrote: > >>>> On Thursday 18 June 2015 02:23 PM, Alexander Sverdlin wrote: > >>>>> According to KeyStone Architecture I2C User Guide, > >>>>> > >>>>> module clock frequency > >>>>> master clock frequency =3D ---------------------- > >>>>> (ICCL + 6) + (ICCH + 6) > >>>>> > >>>>> i.e. "d" in i2c_davinci_calc_clk_dividers() should be fixed and > >>>>> not dependent from module clock prescaler PSC on these SoCs. > >>>>> > >>>>> Signed-off-by: Alexander Sverdlin > >>>>> --- > >>>>> > >>>>> RFC: If someone from TI has an idea how to improve the coverage of = future Keystone > >>>>> revisions -- hints/patches are welcome. The current ID check is bas= ed on > >>>>> Davinci/Keystone datasheets and is at least working on real Keyston= e II. > >>>> > >>>> + Murali who works on Keystone devices in TI. > >>> > >>> + Grygorii > >>> > >>> + Grygorii has been involved in the Keystone related enhancement and > >>> reviewing prior patches. Need to have his ack for this change > >> > >> Any news? > >=20 > > Fixing Grygorii's e-mail id. > >=20 > > Grygorii, let me know if you don't have the thread. I can forward. >=20 > Thanks Sekhar. >=20 > My opinion - it's time for compatible string :) "ti,keystone-i2c".=20 > Especially taking int account two things: > 1) In Datasheet SPRS893B TCI6630K2L Multicore DSP+ARM KeyStone II System-= on-Chip (SoC) (Rev. E)=20 > 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). >=20 > 2) This is not the first time such discussion has been raised. >=20 >=20 > >> > This is not really critical fix. Currently bus rate is lower than ex= pected because of these > >> > calculation errors. The fix maximizes the bus rate. So newer SoCs wi= ll run little bit slower > >> > until support is added to this part of the code. Not really critical= =2E=20 >=20 > 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.=20 > It would be nice to have ref on document in commit message as above. >=20 > - I think, it will be very useful to have same real digits/calculation me= ntioned in > commit message which can show how valuable is the improvement.=20 Alexander, any comments to this feedback? --SUOF0GtieIMvvwua Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJVywdIAAoJEBQN5MwUoCm2beEP/Rr8Y9WKnHRjngKhZa1tcACT B6L3DiEzhb0K318tFl75EL+MIJ41nVdFq4x+Q2UEMuHGePH+y2oEuysosnGb6XN+ bn1yk+CvCVJ/fTRwp9YqjlnErKyAPH2SjsyN5bVLnSYih+/3hkqiCjZRNNAMgIfe 3M06AlDjV2S+10lgbe6VAxpT+kIhvdqQPP4lRIvVy2nLuskiVOqZxQlwXxOUturQ nwOmswAR+T7oxaQYcIafGLenCC3XJddDSFYuSpbsAbzR5pZGs7jXaQPGnogCnSot jh9ozrOcgHFJry+BE7IAFBaLGltv4i//y/kPkE78iUsKBBn3HjUVIDKXnanz61Y9 ESdJJkwz5PXq8EzVhclHk/4iJxVGu8n3BpSQ1bLcaYYKFTGouDG/cJTVD0HsgM1Y 4Iuhr2XulTHLH9YkBXKMKrDoJ9UiXsTH7SSQMBcr26MT5RuPkjqUlAa/m+Ge+E+T mAhs1z/zk691rNSc80DFNeng04Jf6LtUy7Snz4QqKTfCHYVKgOX04x+QZD1Nbk5X kld2+8IqMvWLcPytghcOKzWfm/EmXGFRH85oBoNMHVHVMSWsaPqbg66F9qBFVgFd IukRJbFMSyVbWQK0dGldQ5oZW/dlA5nU6pIK3GQEuexTLYTqSEddMTOB7B5dhRvT 3yWuq0PJsAhCOAhD992q =ZYuu -----END PGP SIGNATURE----- --SUOF0GtieIMvvwua--