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[86.156.77.147]) by smtp.gmail.com with ESMTPSA id 128sm2399338wmi.28.2017.11.03.03.10.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 03 Nov 2017 03:10:59 -0700 (PDT) From: Martyn Welch X-Google-Original-From: Martyn Welch Received: from martyn by hades with local (Exim 4.84_2) (envelope-from ) id 1eAYwD-0002bI-QV; Fri, 03 Nov 2017 10:10:57 +0000 To: u-boot@lists.denx.de Date: Fri, 3 Nov 2017 10:10:48 +0000 Message-Id: <1509703855-9948-2-git-send-email-martyn.welch@collabora.co.uk> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1509703855-9948-1-git-send-email-martyn.welch@collabora.co.uk> References: <1509703855-9948-1-git-send-email-martyn.welch@collabora.co.uk> Cc: Nandor Han Subject: [U-Boot] [PATCH v4 1/8] imx: mxc_i2c: tweak the i2c transfer method X-BeenThere: u-boot@lists.denx.de X-Mailman-Version: 2.1.18 Precedence: list List-Id: U-Boot discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: u-boot-bounces@lists.denx.de Sender: "U-Boot" From: Nandor Han Tweak the i2c transfer to work for devices that want to read data without addressing a register. Signed-off-by: Nandor Han Signed-off-by: Martyn Welch Acked-by: Heiko Schocher Cc: Heiko Schocher Cc: Stefano Babic --- Changes for v2: - Replacing '!= -1' with '>= 0'. drivers/i2c/mxc_i2c.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c index abf1da2..205274e 100644 --- a/drivers/i2c/mxc_i2c.c +++ b/drivers/i2c/mxc_i2c.c @@ -317,16 +317,19 @@ static int i2c_init_transfer_(struct mxc_i2c_bus *i2c_bus, u8 chip, temp |= I2CR_MTX | I2CR_TX_NO_AK; writeb(temp, base + (I2CR << reg_shift)); - /* write slave address */ - ret = tx_byte(i2c_bus, chip << 1); - if (ret < 0) - return ret; - - while (alen--) { - ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff); + if (alen >= 0) { + /* write slave address */ + ret = tx_byte(i2c_bus, chip << 1); if (ret < 0) return ret; + + while (alen--) { + ret = tx_byte(i2c_bus, (addr >> (alen * 8)) & 0xff); + if (ret < 0) + return ret; + } } + return 0; } @@ -537,9 +540,11 @@ static int bus_i2c_read(struct mxc_i2c_bus *i2c_bus, u8 chip, u32 addr, if (ret < 0) return ret; - temp = readb(base + (I2CR << reg_shift)); - temp |= I2CR_RSTA; - writeb(temp, base + (I2CR << reg_shift)); + if (alen >= 0) { + temp = readb(base + (I2CR << reg_shift)); + temp |= I2CR_RSTA; + writeb(temp, base + (I2CR << reg_shift)); + } ret = tx_byte(i2c_bus, (chip << 1) | 1); if (ret < 0) {