On Tue, Jan 23, 2024 at 12:29:57PM -0500, Hugo Villeneuve wrote:
Hi, I would like the following patch to be applied to the stable kernel 6.6:
3837a0379533 serial: sc16is7xx: improve regmap debugfs by using one regmap per port
As noted in https://lore.kernel.org/all/20231211171353.2901416-1-hugo@hugovil.com/raw :
I did not originally add a "Cc: stable" tag for the above mentioned commit, as it was intended only to improve debugging using debugfs. But since then, I have been able to confirm that it also fixes a long standing bug in our system where the Tx interrupt are no longer enabled at some point when transmitting large RS-485 paquets that completely fill the FIFO and thus require multiple and subsequent writes to the FIFO once space in it becomes available. I have been investigating why, but so far I haven't found the exact cause, altough I suspect it has something to do with regmap caching...
It applies cleanly and was tested on this kernel using a custom board with a Variscite IMX8MN NANO SOM, a NewHaven LCD, and two SC16IS752 on a SPI bus. The four UARTs are using RS-485 mode.
Now queued up, thanks.
greg k-h