From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Date: Fri, 06 Mar 2015 22:05:31 +0000 Subject: Re: [PATCH/RFC] i2c: rcar: Fix order of restart and clear status Message-Id: <20150306220531.GA6572@katana> MIME-Version: 1 Content-Type: multipart/mixed; boundary="y0ulUmNC+osPPQO6" List-Id: References: <1424011396-3492-1-git-send-email-ykaneko0929@gmail.com> <20150304040819.GB12776@verge.net.au> In-Reply-To: <20150304040819.GB12776@verge.net.au> To: Simon Horman Cc: Yoshihiro Kaneko , linux-i2c@vger.kernel.org, Magnus Damm , linux-sh@vger.kernel.org --y0ulUmNC+osPPQO6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > I asked Kataoka-san about this and his response was as follows: Thanks, Simon! > If system(CPU) is busy, the driver can't clear the status register soon > after kicking start. >=20 > If sequence of first start is as follows, there is a problem. > Because H/W starts by 1. > But sequence of re-start is as follows, there is no problem. > Because H/W starts by 2. >=20 > 1. Issue START condition by ESG bit of ICMCR register. > <--- If there is too much time, H/W finish transmitting > and set status in status register. > 2. Clear interrupt status (ICMSR). > 3. Open interrupt mask. > 4. Wait interrupt. > <--- If status is cleared, interrupt does not occur. I understand. I'll add this explanation to the patch and apply it soon. --y0ulUmNC+osPPQO6 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJU+iSrAAoJEBQN5MwUoCm2NYIP/jD/F4+ibWcVxTlhgrnDROBN Bah6XoAvdFgU1sWUeaHSiI9s0uhMoXHTn7c1dGlDiPrTgyBD45EdFsVaahKPulwQ gfSTa/RvUCy5/+IrLRVKPWs4kqsCJwCr7SVQASWAHa3F3iRuxp9/YlaJBQkLpJjA 8dJjmCfqNMihny+DhuAgQczFTCY3oTdo1VRgaxnEnQKUtks22WRmuvDUhSWNF0zz y1rkKWbUZxaVeg/BCkBU2jHIw28Hsp+RWLGSDqCcfukgItUtgQ0J9TWEXw0Jx3Sq 9euSzQ85D3eWvqcme1J+DykvSM5JBUjkpfEzmLr2LhzDiiPr1niEac3UEb2E9YER W490G7caz/uhi4p8vJ1e7yguAz5/MNJ3yz0ZQs6A3Nbfysl49Dhse9/pkU8B4Vdo rvVaSVCr/NR+r43bxtBvVUOFvZGl93ZxxBFpt6vGgvkTxd9yNr68Lj/OjMg+mlIQ yLKshjFfF4tBsd1f1bQrPTEEB0RboyWtFl/MjtAwO2H5VBKY2vnT34/5wiXrufNE Cxj8wnp1f4VI1jPWscZEvO6+bl4iWcK6+QZsfnk2tMGhZvaCzy1D7YJwTtGdJPU8 iKkS2L48LTV4D+9pR8T99lV+QjjqSb8PjSzFiuF4scFk3HtU8zj5erLbZhpqmmbj fyQYtlZ4VOvVvYNaLOIK =E2vm -----END PGP SIGNATURE----- --y0ulUmNC+osPPQO6--