From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932358AbeE3UyE (ORCPT ); Wed, 30 May 2018 16:54:04 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:43032 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932238AbeE3UyC (ORCPT ); Wed, 30 May 2018 16:54:02 -0400 Subject: Re: [PATCH v7 5/7] drivers/i2c: Add transfer implementation for FSI algorithm To: Andy Shevchenko Cc: linux-i2c , Linux Kernel Mailing List , devicetree , Wolfram Sang , Rob Herring , Benjamin Herrenschmidt , Joel Stanley , Mark Rutland , Greg Kroah-Hartman , "Edward A. James" References: <1527632665-25707-1-git-send-email-eajames@linux.vnet.ibm.com> <1527632665-25707-6-git-send-email-eajames@linux.vnet.ibm.com> From: Eddie James Date: Wed, 30 May 2018 15:53:53 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-TM-AS-GCONF: 00 x-cbid: 18053020-0012-0000-0000-0000165A7179 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00009099; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000264; SDB=6.01039983; UDB=6.00532322; IPR=6.00819117; MB=3.00021382; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-30 20:53:59 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18053020-0013-0000-0000-0000530BEA02 Message-Id: <710a9afe-e268-9dbc-5183-9793d4eae2d3@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-30_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1805220000 definitions=main-1805300221 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/29/2018 07:08 PM, Andy Shevchenko wrote: > On Wed, May 30, 2018 at 1:24 AM, Eddie James wrote: >> From: "Edward A. James" >> >> Execute I2C transfers from the FSI-attached I2C master. Use polling >> instead of interrupts as we have no hardware IRQ over FSI. >> + if (msg->flags & I2C_M_RD) >> + cmd |= I2C_CMD_READ; > I think we have a helper for this, though not sure. Didn't see any other I2C drivers using any helper for msg->flags. > >> +static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg, >> + u8 fifo_count) >> +{ >> + int write; >> + int rc = 0; > Redundant assignment. > >> + struct fsi_i2c_master *i2c = port->master; >> + int bytes_to_write = i2c->fifo_size - fifo_count; >> + int bytes_remaining = msg->len - port->xfrd; >> + if (bytes_to_write > bytes_remaining) >> + bytes_to_write = bytes_remaining; > _write = min(_write, _remaining); > >> + while (bytes_to_write > 0) { >> + write = bytes_to_write; >> + /* fsi limited to max 4 byte aligned ops */ >> + if (bytes_to_write > 4) >> + write = 4; >> + else if (write == 3) >> + write = 2; > write = min_t(int, 4, rounddown_pow_of_two(bytes_to_write)); > > Also check it carefully, it might be optimized even more, though I > didn't think much. I think it is more readable this way, and I'm not convinced the min(rounddown()) is faster. I did however add a common function to do this check since it's performed in both the read and write fifo functions. Let me know what you think on v8. Thanks, Eddie