From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1CE94C433EF for ; Wed, 10 Nov 2021 08:59:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 01FB5610A8 for ; Wed, 10 Nov 2021 08:59:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230256AbhKJJBs (ORCPT ); Wed, 10 Nov 2021 04:01:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229831AbhKJJBr (ORCPT ); Wed, 10 Nov 2021 04:01:47 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B5B86C061764 for ; Wed, 10 Nov 2021 00:59:00 -0800 (PST) Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1mkjRZ-0001aH-DR; Wed, 10 Nov 2021 09:58:57 +0100 Received: from ore by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1mkjRZ-0000EE-1A; Wed, 10 Nov 2021 09:58:57 +0100 Date: Wed, 10 Nov 2021 09:58:57 +0100 From: Oleksij Rempel To: minyard@acm.org Cc: Pengutronix Kernel Team , linux-i2c@vger.kernel.org, Andrew Manley , linux-kernel@vger.kernel.org, Corey Minyard Subject: Re: [PATCH 2/3] i2c:imx: Add an extra read at the end of an I2C slave read Message-ID: <20211110085856.GD12195@pengutronix.de> References: <20211005003216.2670632-1-minyard@acm.org> <20211005003216.2670632-3-minyard@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20211005003216.2670632-3-minyard@acm.org> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 09:58:34 up 265 days, 12:22, 128 users, load average: 0.16, 0.15, 0.16 User-Agent: Mutt/1.10.1 (2018-07-13) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::c0 X-SA-Exim-Mail-From: ore@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-i2c@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org On Mon, Oct 04, 2021 at 07:32:15PM -0500, minyard@acm.org wrote: > From: Corey Minyard > > The I2C slave interface expects that the driver will read ahead one > byte. The IMX driver/device doesn't do this, but simulate it so that > read operations get their index set correctly. > > Signed-off-by: Corey Minyard > Tested-by: Andrew Manley > Reviewed-by: Andrew Manley Reviewed-by: Oleksij Rempel > --- > drivers/i2c/busses/i2c-imx.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c > index 97369fe48b30..26a04dc0590b 100644 > --- a/drivers/i2c/busses/i2c-imx.c > +++ b/drivers/i2c/busses/i2c-imx.c > @@ -769,6 +769,15 @@ static irqreturn_t i2c_imx_slave_handle(struct imx_i2c_struct *i2c_imx, > ctl &= ~I2CR_MTX; > imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR); > imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR); > + > + /* > + * The i2c slave interface requires one extra dummy > + * read at the end to keep things in line. See the > + * I2C slave docs for details. > + */ > + i2c_imx_slave_event(i2c_imx, > + I2C_SLAVE_READ_PROCESSED, &value); > + > i2c_imx_slave_finish_op(i2c_imx); > return IRQ_HANDLED; > } > -- > 2.25.1 > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |