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[220.135.95.34]) by smtp.gmail.com with ESMTPSA id v10-20020a63ac0a000000b00563e1ef0491sm876119pge.8.2023.09.14.03.13.45 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Sep 2023 03:13:45 -0700 (PDT) From: AceLan Kao To: kernel-team@lists.ubuntu.com Subject: [PATCH 1/1][SRU][M] UBUNTU: SAUCE: platform/x86: dell-uart-backlight: add small delay after write command Date: Thu, 14 Sep 2023 18:13:41 +0800 Message-Id: <20230914101341.233733-2-acelan.kao@canonical.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230914101341.233733-1-acelan.kao@canonical.com> References: <20230914101341.233733-1-acelan.kao@canonical.com> MIME-Version: 1.0 Received-SPF: pass client-ip=209.85.210.45; envelope-from=acelan@gmail.com; helo=mail-ot1-f45.google.com X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: "Chia-Lin Kao (AceLan)" BugLink: https://bugs.launchpad.net/bug/2035299 After applying fbf84fb368923 ("UBUNTU: SAUCE: platform/x86: dell-uart-backlight: replace chars_in_buffer() with flush_chars()"), it seems that the read() command may fail to receive a response, even when increasing the retry times. It never gets a response when it fails. To fix this, try adding a small delay after the write() function as a workaround. Fixes: fbf84fb368923 ("UBUNTU: SAUCE: platform/x86: dell-uart-backlight: replace chars_in_buffer() with flush_chars()") Signed-off-by: Chia-Lin Kao (AceLan) --- drivers/platform/x86/dell/dell-uart-backlight.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/platform/x86/dell/dell-uart-backlight.c b/drivers/platform/x86/dell/dell-uart-backlight.c index 120701e5b8b13..c489f7997767f 100644 --- a/drivers/platform/x86/dell/dell-uart-backlight.c +++ b/drivers/platform/x86/dell/dell-uart-backlight.c @@ -248,6 +248,7 @@ static int dell_uart_set_bl_power(struct backlight_device *bd, int power) } dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len); + msleep(1); rx_len = dell_uart_read(uart, bl_cmd->ret, bl_cmd->rx_len); mutex_unlock(&dell_pdata->brightness_mutex); @@ -275,6 +276,7 @@ static int dell_uart_get_brightness(struct backlight_device *bd) } dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len); + msleep(1); rx_len = dell_uart_read(uart, bl_cmd->ret, bl_cmd->rx_len); mutex_unlock(&dell_pdata->brightness_mutex); @@ -304,6 +306,7 @@ static int dell_uart_update_status(struct backlight_device *bd) } dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len); + msleep(1); rx_len = dell_uart_read(uart, bl_cmd->ret, bl_cmd->rx_len); mutex_unlock(&dell_pdata->brightness_mutex); @@ -330,6 +333,7 @@ static int dell_uart_show_firmware_ver(struct dell_uart_backlight *dell_pdata) } dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len); + msleep(1); while (retry-- > 0) { /* first byte is data length */ dell_uart_read(uart, bl_cmd->ret, 1); @@ -371,6 +375,7 @@ static int dell_uart_get_display_mode(struct dell_uart_backlight *dell_pdata) } dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len); + msleep(1); rx_len = dell_uart_read(uart, bl_cmd->ret, bl_cmd->rx_len); mutex_unlock(&dell_pdata->brightness_mutex);