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([106.202.98.254]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3607ee0cab0sm15999208eec.3.2026.10.17.00.37.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 17 Oct 2026 00:37:44 -0700 (PDT) From: chitranshmandhaniya@gmail.com To: hansg@kernel.org, ilpo.jarvinen@linux.intel.com Cc: platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, Chitransh_Mandhaniya@dell.com Subject: [PATCH v4 1/2] platform/x86: dell-uart-backlight: extract dell_uart_bl_receive_data() helper Date: Sat, 17 Oct 2026 13:07:03 +0530 Message-ID: <20261017073704.606497-2-chitranshmandhaniya@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261017073704.606497-1-chitranshmandhaniya@gmail.com> References: <20261004110333.5790-1-chitranshmandhaniya@gmail.com> <20261017073704.606497-1-chitranshmandhaniya@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chitransh Mandhaniya Factor the response-byte accumulation and checksum validation out of dell_uart_bl_receive() into a standalone dell_uart_bl_receive_data() helper. The helper returns the number of bytes consumed from the input buffer. The caller inspects dell_bl->status for the outcome: -EBUSY frame still incomplete 0 frame received and checksum valid -EIO checksum mismatch This is a preparatory refactor for adding stray-byte recovery in the next patch. No functional change. Signed-off-by: Chitransh Mandhaniya --- .../platform/x86/dell/dell-uart-backlight.c | 42 ++++++++++++------- 1 file changed, 27 insertions(+), 15 deletions(-) diff --git a/drivers/platform/x86/dell/dell-uart-backlight.c b/drivers/platform/x86/dell/dell-uart-backlight.c index f323a667dc2d..5f01ad108338 100644 --- a/drivers/platform/x86/dell/dell-uart-backlight.c +++ b/drivers/platform/x86/dell/dell-uart-backlight.c @@ -205,20 +205,13 @@ static const struct backlight_ops dell_uart_backlight_ops = { .get_brightness = dell_uart_get_brightness_op, }; -static size_t dell_uart_bl_receive(struct serdev_device *serdev, const u8 *data, size_t len) +/* Process received UART data; returns number of bytes consumed. */ +static size_t dell_uart_bl_receive_data(struct dell_uart_backlight *dell_bl, + const u8 *data, size_t len) { - struct dell_uart_backlight *dell_bl = serdev_device_get_drvdata(serdev); size_t i; u8 csum; - dev_dbg(dell_bl->dev, "Recv: %*ph\n", (int)len, data); - - /* Throw away unexpected bytes / remainder of response after an error */ - if (dell_bl->status != -EBUSY) { - dev_warn(dell_bl->dev, "Bytes received out of band, dropping them.\n"); - return len; - } - i = 0; while (i < len && dell_bl->resp_idx != dell_bl->resp_len) { dell_bl->resp[dell_bl->resp_idx] = data[i++]; @@ -231,7 +224,7 @@ static size_t dell_uart_bl_receive(struct serdev_device *serdev, const u8 *data, dev_err(dell_bl->dev, "Response length %d out if range %d - %d\n", dell_bl->resp_len, MIN_RESP_LEN, dell_bl->resp_max_len); dell_bl->status = -EIO; - goto wakeup; + return i; } break; case RESP_CMD: /* CMD byte */ @@ -239,7 +232,7 @@ static size_t dell_uart_bl_receive(struct serdev_device *serdev, const u8 *data, dev_err(dell_bl->dev, "Response cmd 0x%02x != pending 0x%02x\n", dell_bl->resp[RESP_CMD], dell_bl->pending_cmd); dell_bl->status = -EIO; - goto wakeup; + return i; } break; } @@ -247,7 +240,7 @@ static size_t dell_uart_bl_receive(struct serdev_device *serdev, const u8 *data, } if (dell_bl->resp_idx != dell_bl->resp_len) - return len; /* Response not complete yet */ + return i; /* Response not complete, status stays -EBUSY */ csum = dell_uart_checksum(dell_bl->resp, dell_bl->resp_len - 1); if (dell_bl->resp[dell_bl->resp_len - 1] == csum) { @@ -257,11 +250,30 @@ static size_t dell_uart_bl_receive(struct serdev_device *serdev, const u8 *data, dell_bl->resp[dell_bl->resp_len - 1], csum); dell_bl->status = -EIO; } -wakeup: - wake_up(&dell_bl->wait_queue); return i; } +static size_t dell_uart_bl_receive(struct serdev_device *serdev, const u8 *data, size_t len) +{ + struct dell_uart_backlight *dell_bl = serdev_device_get_drvdata(serdev); + size_t ret; + + dev_dbg(dell_bl->dev, "Recv: %*ph\n", (int)len, data); + + /* Throw away unexpected bytes / remainder of response after an error */ + if (dell_bl->status != -EBUSY) { + dev_warn(dell_bl->dev, "Bytes received out of band, dropping them.\n"); + return len; + } + + ret = dell_uart_bl_receive_data(dell_bl, data, len); + if (dell_bl->status == -EBUSY) + return ret; /* Response not complete yet, waiting for more data */ + + wake_up(&dell_bl->wait_queue); + return ret; +} + static const struct serdev_device_ops dell_uart_bl_serdev_ops = { .receive_buf = dell_uart_bl_receive, .write_wakeup = serdev_device_write_wakeup, -- 2.43.0