Thanks Tony. > -----Original Message----- > From: Tony Lindgren [mailto:tony@xxxxxxxxxxx] > Sent: Wednesday, January 27, 2010 11:03 PM > To: Shilimkar, Santosh > Cc: linux-omap@xxxxxxxxxxxxxxx; Woodruff, Richard; Ghorai, Sukumar > Subject: Re: [PATCH] OMAP: UART: fix full-fifo write abort > > * Santosh Shilimkar <santosh.shilimkar@xxxxxx> [100127 02:34]: > > This patch is addition to the already merged commit on non-empty > > uart fifo read abort. "ce13d4716a276f4331d78ba28a5093a63822ab95" > > > > OMAP3630 and OMAP4430 UART IP blocks have a restriction on TX FIFO > > too. If you try to write to the tx fifo when it is full, the system aborts. > > > > This can be easily reproducible by not suppressing interconnect errors or > > long duartion testing where continous prints over console from multiple > > threads . This patch is addressing the issue by ensuring that write is > > not issued while fifo is full. A timeout is added to avoid any hang > > on fifo-full for 10 mS which is unlikely case. > > > > Patch is validated on OMAP3630 and OMAP4 SDP. > > Can you do this as needed based on the FIFO interrupt? Fifo-interrupt based case is already handled in generic driver. Kernel prints will still use non-interrupt mode which can still create the issue. At least performance use cases like MODEM, BT can make use of DMA based UART transfer where this limitation won't be there. > > > Signed-off-by: Woodruff Richard <r-woodruff2@xxxxxx> > > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx> > > CC: Ghorai Sukumar <s-ghorai@xxxxxx> > > --- > > arch/arm/mach-omap2/serial.c | 30 ++++++++++++++++++++++++++++-- > > 1 files changed, 28 insertions(+), 2 deletions(-) > > > > --- a/arch/arm/mach-omap2/serial.c > > +++ b/arch/arm/mach-omap2/serial.c > > <snip> > > > +static void serial_out_override(struct uart_port *up, int offset, int value) > > +{ > > + unsigned int status, tmout = 10000; > > + > > + /* Wait up to 10ms for the character(s) to be sent. */ > > + do { > > + status = __serial_read_reg(up, UART_LSR); > > + if (--tmout == 0) > > + break; > > + udelay(1); > > + } while (!(status & UART_LSR_THRE)); > > + > > + __serial_write_reg(up, offset, value); > > Do you really want to have a udelay on every TX? > > How about: > > status = __serial_read_reg(up, UART_LSR); > while (!(status & UART_LSR_THRE)) { > > if (--tmout == 0) > break; > > udelay(1); > status = __serial_read_reg(up, UART_LSR); > } > __serial_write_reg(up, offset, value); This is good. Will fix this. -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
