serial: max310x: improve crystal stable clock detection
Some people are seeing a warning similar to this when using a crystal: max310x 11-006c: clock is not stable yet The datasheet doesn't mention the maximum time to wait for the clock to be stable when using a crystal, and it seems that the 10ms delay in the driver is not always sufficient. Jan Kundrát reported that it took three tries (each separated by 10ms) to get a stable clock. Modify behavior to check stable clock ready bit multiple times (20), and waiting 10ms between each try. Note: the first draft of the driver originally used a 50ms delay, without checking the clock stable bit. Then a loop with 1000 retries was implemented, each time reading the clock stable bit. Fixes: 4cf9a888 ("serial: max310x: Check the clock readiness") Cc: stable@vger.kernel.org Suggested-by:Jan Kundrát <jan.kundrat@cesnet.cz> Link: https://www.spinics.net/lists/linux-serial/msg35773.html Link: https://lore.kernel.org/all/20240110174015.6f20195fde08e5c9e64e5675@hugovil.com/raw Link: https://github.com/boundarydevices/linux/commit/e5dfe3e4a751392515d78051973190301a37ca9a Signed-off-by:
Hugo Villeneuve <hvilleneuve@dimonoff.com> Link: https://lore.kernel.org/r/20240116213001.3691629-3-hugo@hugovil.com Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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