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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07A64C433FE for ; Mon, 17 Jan 2022 17:12:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243476AbiAQRMT (ORCPT ); Mon, 17 Jan 2022 12:12:19 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:56292 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242785AbiAQRIN (ORCPT ); Mon, 17 Jan 2022 12:08:13 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C1C87612C5; Mon, 17 Jan 2022 17:08:12 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55BFEC36AF8; Mon, 17 Jan 2022 17:08:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1642439292; bh=P8JodIRX2uzjywT3FD6+DpyuTrOHA3GSKST3Iwdgot4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VLmxv1pjJvz+H9yO8jJvIg+/mp8Vmcjm2EwZ9oz2m9sY8+Hg5zsADln4vH0bsE+hY B5rS8K01uZLCGA+rVfcHkWMGz3cyjSbbLw9IaFfe++PU8QGQhFgn06I90utGbk3B7n VzbuKRtIaFlDNM0/39XMKDYsQIhf8lf3EPQ+NVtFapslRhUz2zB/C6jBA5qG1Hjjru HL5MwOugstyOmS0KIR1k2tm8rsyDXNnsfNr2GKDzguoRWBBb6ed3Hqppul116LM+cU lKhCn1F/ZU2T600yJuVRmiU8eQiJeMBzP9EdtH9hOzn2OHwJPsqDJ6G/3pW0cnSF1P HKRM9fGNY4tOA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Joakim Tjernlund , Scott Wood , Wolfram Sang , Sasha Levin , chris.packham@alliedtelesis.co.nz, linux-i2c@vger.kernel.org Subject: [PATCH AUTOSEL 4.4 07/12] i2c: mpc: Correct I2C reset procedure Date: Mon, 17 Jan 2022 12:07:51 -0500 Message-Id: <20220117170757.1473318-7-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220117170757.1473318-1-sashal@kernel.org> References: <20220117170757.1473318-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Joakim Tjernlund [ Upstream commit ebe82cf92cd4825c3029434cabfcd2f1780e64be ] Current I2C reset procedure is broken in two ways: 1) It only generate 1 START instead of 9 STARTs and STOP. 2) It leaves the bus Busy so every I2C xfer after the first fixup calls the reset routine again, for every xfer there after. This fixes both errors. Signed-off-by: Joakim Tjernlund Acked-by: Scott Wood Signed-off-by: Wolfram Sang Signed-off-by: Sasha Levin --- drivers/i2c/busses/i2c-mpc.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c index 2e083a71c2215..988ea9df6654c 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -107,23 +107,30 @@ static irqreturn_t mpc_i2c_isr(int irq, void *dev_id) /* Sometimes 9th clock pulse isn't generated, and slave doesn't release * the bus, because it wants to send ACK. * Following sequence of enabling/disabling and sending start/stop generates - * the 9 pulses, so it's all OK. + * the 9 pulses, each with a START then ending with STOP, so it's all OK. */ static void mpc_i2c_fixup(struct mpc_i2c *i2c) { int k; - u32 delay_val = 1000000 / i2c->real_clk + 1; - - if (delay_val < 2) - delay_val = 2; + unsigned long flags; for (k = 9; k; k--) { writeccr(i2c, 0); - writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN); + writeb(0, i2c->base + MPC_I2C_SR); /* clear any status bits */ + writeccr(i2c, CCR_MEN | CCR_MSTA); /* START */ + readb(i2c->base + MPC_I2C_DR); /* init xfer */ + udelay(15); /* let it hit the bus */ + local_irq_save(flags); /* should not be delayed further */ + writeccr(i2c, CCR_MEN | CCR_MSTA | CCR_RSTA); /* delay SDA */ readb(i2c->base + MPC_I2C_DR); - writeccr(i2c, CCR_MEN); - udelay(delay_val << 1); + if (k != 1) + udelay(5); + local_irq_restore(flags); } + writeccr(i2c, CCR_MEN); /* Initiate STOP */ + readb(i2c->base + MPC_I2C_DR); + udelay(15); /* Let STOP propagate */ + writeccr(i2c, 0); } static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing) -- 2.34.1