From patchwork Mon Jan 24 18:42:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 535751 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 93FEAC433FE for ; Mon, 24 Jan 2022 20:43:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359028AbiAXUng (ORCPT ); Mon, 24 Jan 2022 15:43:36 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:36222 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1389502AbiAXUl1 (ORCPT ); Mon, 24 Jan 2022 15:41:27 -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 96A3A615C2; Mon, 24 Jan 2022 20:41:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72374C340E5; Mon, 24 Jan 2022 20:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643056884; bh=VpOIpWuYU5r7PoaTzGcmVyr0EObttdwQ5irv2gBTbpo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nx4pf0ettV0f2VPZ1unJcivzxhh2puzrmCzYb2PzWNlQEu81W2g+6EQuXh7BOVwQ/ Yd/00ykEL8W4s15vY2/JqJzsTH/nAnYNXDPcduetYchJXURS6MdiOfdXmQR/2pBA3o 4TmcQWYnpx8sJr/jkvTWAH52RSUlh3o6+8NDRq5E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joakim Tjernlund , Scott Wood , Wolfram Sang , Sasha Levin Subject: [PATCH 5.15 631/846] i2c: mpc: Correct I2C reset procedure Date: Mon, 24 Jan 2022 19:42:28 +0100 Message-Id: <20220124184122.797859418@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124184100.867127425@linuxfoundation.org> References: <20220124184100.867127425@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@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 db26cc36e13fe..6c698c10d3cdb 100644 --- a/drivers/i2c/busses/i2c-mpc.c +++ b/drivers/i2c/busses/i2c-mpc.c @@ -119,23 +119,30 @@ static inline void writeccr(struct mpc_i2c *i2c, u32 x) /* 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_mpc_wait_sr(struct mpc_i2c *i2c, int mask)