forked from Minki/linux
mainlining shenanigans
0e5ec4140c
Issue where unprintable characters can occur or output is cut off over the serial uart / linux console depending on timing. Problem occurs when changing the serial baud rate when setting up the new console.The bcm63xx driver does a disable and flush of the uart tx fifo while there is data still in the tx fifo. If the tx fifo still has data it is trying to send out, we need to wait until it is empty before disabling and flushing the uart. When we now go to change the uart parameters including speed we check if there is data currently in the tx fifo.If there is was mdelay(10) and check again.If it tries 3 times and still has data in it we just continue and sacrifice the tx fifo buffer. A cleaner and more preferred approach would be to remove : - spin_lock_irqsave() - bcm_uart_disable() - bcm_uart_flush() However it is not clear if the author put those in to fix another underlying issue.As a result this solution is a safer approach. Output before the fix: [0.306000] 14e00520.serial: ttyS0 at MMIO 0x14e00520 (irq = 9, base_baud = 1687500) is a° 0.315000] console[ttyS0] enabled Output verified after the fix: [0.315000] 14e00520.serial: ttyS0 at MMIO 0x14e00520 (irq = 9, base_baud = 1687500) is a bcm63xx_uart [0.334000] console[ttyS0] enabled Signed-off-by: Russell Enderby <rte@gdn.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| fs | ||
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| kernel | ||
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| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| README | ||
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.