This bug is awaiting verification that the linux-oem-6.5/6.5.0-1004.4 kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-jammy-linux-oem-6.5' to 'verification-done- jammy-linux-oem-6.5'. If the problem still exists, change the tag 'verification-needed-jammy-linux-oem-6.5' to 'verification-failed-jammy- linux-oem-6.5'.
If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you! ** Tags added: kernel-spammed-jammy-linux-oem-6.5-v2 verification-needed-jammy-linux-oem-6.5 -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/2035299 Title: dell-uart-backlight fails to communicate with the scalar IC somtimes. Status in HWE Next: New Status in linux package in Ubuntu: In Progress Status in linux-oem-6.5 package in Ubuntu: Invalid Status in linux source package in Jammy: Invalid Status in linux-oem-6.5 source package in Jammy: In Progress Status in linux source package in Mantic: In Progress Status in linux-oem-6.5 source package in Mantic: Invalid Bug description: [Impact] Boots up the system and sometimes we can see below messages and that leads to backlight driver doesn't get loaded. [ 86.424880] dell_uart_backlight:dell_uart_get_display_mode:tx: 6a 10 85 [ 86.603936] [7439] dell_uart_backlight:dell_uart_get_display_mode:rx: NULL [ 87.596047] dell_uart_backlight:dell_uart_get_display_mode:tx: 6a 10 85 [ 87.775209] [7439] dell_uart_backlight:dell_uart_get_display_mode:rx: NULL [Fix] After applying the patch below, 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. fbf84fb368923 ("UBUNTU: SAUCE: platform/x86: dell-uart-backlight: replace chars_in_buffer() with flush_chars()") To fix this, try adding a small delay after the write() function as a workaround. [Test case] 1. Add dell_uart_backlight.dyndbg="+pt" to the kernel cmdline 2. Boots up the system and check dmesg 3. Make sure there is no dell_uart_backlight rx NULL message in dmesg 4. Try to unload/reload dell_uart_backlight couple times and check dmesg again [Where problems could occur] sleep for 1ms is pretty short that it's not possible to lead to messages loss. To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/2035299/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
