Andrew,
Would you please take a moment to review this patch I sent last month?
I'd like for it to be incorporated into 2.6.37, but I'm having a hard
time finding someone to consider it.
Thanks.
On Fri, Aug 20, 2010 at 1:45 PM, Timur Tabi <ti...@freescale.com> wrote:
> hvc_console_print() calls the HVC client driver's put_chars() callback
> to write some characters to the console. If the callback returns 0, that
> indicates that no characters were written (perhaps the output buffer is
> full), but hvc_console_print() treats that as an error and discards the
> rest of the buffer.
>
> So change hvc_console_print() to just loop and call put_chars() again if it
> returns a 0 return code.
>
> This change makes hvc_console_print() behave more like hvc_push(), which
> does check for a 0 return code and re-schedules itself.
>
> Signed-off-by: Timur Tabi <ti...@freescale.com>
> ---
> drivers/char/hvc_console.c | 19 ++++++++++++++++++-
> 1 files changed, 18 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
> index fa27d16..b4deffd 100644
> --- a/drivers/char/hvc_console.c
> +++ b/drivers/char/hvc_console.c
> @@ -3,6 +3,7 @@
> * Copyright (C) 2001 Paul Mackerras <pau...@au.ibm.com>, IBM
> * Copyright (C) 2004 Benjamin Herrenschmidt <b...@kernel.crashing.org>, IBM
> Corp.
> * Copyright (C) 2004 IBM Corporation
> + * Copyright 2009 Freescale Semiconductor, Inc.
> *
> * Additional Author(s):
> * Ryan S. Arnold <r...@us.ibm.com>
> @@ -141,6 +142,7 @@ static void hvc_console_print(struct console *co, const
> char *b,
> char c[N_OUTBUF] __ALIGNED__;
> unsigned i = 0, n = 0;
> int r, donecr = 0, index = co->index;
> + unsigned int timeout = 1000000; /* Keep trying for up to one second */
>
> /* Console access attempt outside of acceptable console range. */
> if (index >= MAX_NR_HVC_CONSOLES)
> @@ -152,6 +154,10 @@ static void hvc_console_print(struct console *co, const
> char *b,
>
> while (count > 0 || i > 0) {
> if (count > 0 && i < sizeof(c)) {
> + /* If the local buffer (c) is not full, then copy some
> + * bytes from the input buffer to it. We stop when the
> + * local buffer is full. \n is converted to \r\n.
> + */
> if (b[n] == '\n' && !donecr) {
> c[i++] = '\r';
> donecr = 1;
> @@ -162,14 +168,25 @@ static void hvc_console_print(struct console *co, const
> char *b,
> }
> } else {
> r = cons_ops[index]->put_chars(vtermnos[index], c, i);
> - if (r <= 0) {
> + if (r < 0) {
> /* throw away chars on error */
> i = 0;
> } else if (r > 0) {
> i -= r;
> if (i > 0)
> memmove(c, c+r, i);
> + } else {
> + /* If r == 0, then the client driver didn't do
> + * anything, so wait 1us and try again. If we
> + * time out, then just exit.
> + */
> + if (!--timeout)
> + return;
> + udelay(1);
> + continue;
> }
> + /* Reset the timeout */
> + timeout = 1000000;
> }
> }
> }
> --
> 1.7.0.1
>
>
> _______________________________________________
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> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>
--
Timur Tabi
Linux kernel developer at Freescale
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