Hi Dave, On Thu, May 21, 2015 at 04:37:49PM +0100, Dave Martin wrote: > Commit 734745caeb9f155ab58918834a8c70e83fa6afd3 serial/amba-pl011: > (Activate TX IRQ passively) introduces a race which causes the driver > sometimes to attempt to write a character to the TX FIFO when the FIFO > is already full. > > The PL011 does not guarantee its behaviour when the FIFO is overfilled. > In practice, this can cause duplicate and/or dropped characters to be > output on the wire. The problem is common enough to be readily > observable on the ARM Juno platform when the PL011 UART is used as > the console and DMA is not in use. > > This patch fixes this problem by always polling for space before each > character is written to the FIFO. > > This will be amended to a less brute-force approach in a later commit, > but this patch should help ensure correct behaviour for now. > > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> > --- Do you know if this patch has been applied anywhere? Without it, poor old systemd has an identity crisis when run under 4.1-rc4, alternating between Scottish: [ OK ] Stopped Regularr background proogram processing daemon. and Old English: [ OK ] Started Tell Pllymouth To Writee Out Runtime Data. Starting Copy rules geneerated while thee root was ro... Will -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
