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[109.186.136.71]) by smtp.googlemail.com with ESMTPSA id v1-20020aa7d641000000b0042acd78014esm10230533edr.11.2022.05.25.00.48.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 May 2022 00:48:42 -0700 (PDT) From: Michael Zaidman To: jikos@kernel.org, benjamin.tissoires@redhat.com, wsa@kernel.org Cc: linux-kernel@vger.kernel.org, linux-input@vger.kernel.org, linux-i2c@vger.kernel.org, champagne.guillaume.c@gmail.com, mathieu.gallichand@sonatest.com, Michael Zaidman Subject: [PATCH v1 1/5] HID: ft260: ft260_xfer_status routine cleanup Date: Wed, 25 May 2022 10:47:53 +0300 Message-Id: <20220525074757.7519-2-michael.zaidman@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220525074757.7519-1-michael.zaidman@gmail.com> References: <20220525074757.7519-1-michael.zaidman@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org After clarifying with FTDI's support, it turned out that the error condition (bit 1) in byte 1 of the i2c status HID report is a status bit reflecting all error conditions. When bits 2, 3, or 4 are raised to 1, bit 1 is set to 1 also. Since the ft260_xfer_status routine tests the error condition bit and exits in the case of an error, the program flow never reaches the conditional expressions for 2, 3, and 4 bits when any of them indicates an error state. Though these expressions are never evaluated to true, they are checked several times per IO, increasing the ft260_xfer_status polling cycle duration. The patch removes the conditional expressions for 2, 3, and 4 bits in byte 1 of the i2c status HID report. Signed-off-by: Michael Zaidman --- drivers/hid/hid-ft260.c | 30 ++++++++++-------------------- 1 file changed, 10 insertions(+), 20 deletions(-) diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c index 79505c64dbfe..a35201d68b15 100644 --- a/drivers/hid/hid-ft260.c +++ b/drivers/hid/hid-ft260.c @@ -313,27 +313,17 @@ static int ft260_xfer_status(struct ft260_device *dev) if (report.bus_status & FT260_I2C_STATUS_CTRL_BUSY) return -EAGAIN; - if (report.bus_status & FT260_I2C_STATUS_BUS_BUSY) - return -EBUSY; - - if (report.bus_status & FT260_I2C_STATUS_ERROR) + /* + * The error condition (bit 1) is a status bit reflecting any + * error conditions. When any of the bits 2, 3, or 4 are raised + * to 1, bit 1 is also set to 1. + */ + if (report.bus_status & FT260_I2C_STATUS_ERROR) { + hid_err(hdev, "i2c bus error: %#02x\n", report.bus_status); return -EIO; + } - ret = -EIO; - - if (report.bus_status & FT260_I2C_STATUS_ADDR_NO_ACK) - ft260_dbg("unacknowledged address\n"); - - if (report.bus_status & FT260_I2C_STATUS_DATA_NO_ACK) - ft260_dbg("unacknowledged data\n"); - - if (report.bus_status & FT260_I2C_STATUS_ARBITR_LOST) - ft260_dbg("arbitration loss\n"); - - if (report.bus_status & FT260_I2C_STATUS_CTRL_IDLE) - ret = 0; - - return ret; + return 0; } static int ft260_hid_output_report(struct hid_device *hdev, u8 *data, @@ -376,7 +366,7 @@ static int ft260_hid_output_report_check_status(struct ft260_device *dev, break; } while (--try); - if (ret == 0 || ret == -EBUSY) + if (ret == 0) return 0; ft260_i2c_reset(hdev);