lkml.org 
[lkml]   [2011]   [Nov]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [alsa-devel] [PATCH] hda - fail ELD reading early
At Tue, 22 Nov 2011 16:46:23 +0800,
Wu Fengguang wrote:
>
> With the ELD repoll mechanism, we can (and should) fail the ELD reading
> immediately when find something obviously wrong and let the caller retry
> after some delay.
>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> ---
> sound/pci/hda/hda_eld.c | 28 +++++++++++++++++++---------
> 1 file changed, 19 insertions(+), 9 deletions(-)
>
> --- linux.orig/sound/pci/hda/hda_eld.c 2011-11-22 16:02:58.000000000 +0800
> +++ linux/sound/pci/hda/hda_eld.c 2011-11-22 16:36:10.000000000 +0800
> @@ -347,18 +347,28 @@ int snd_hdmi_get_eld(struct hdmi_eld *el
>
> for (i = 0; i < size; i++) {
> unsigned int val = hdmi_get_eld_data(codec, nid, i);
> + /*
> + * Graphics driver might be writing to ELD buffer right now.
> + * Just abort. The caller will repoll after a while.
> + */
> if (!(val & AC_ELDD_ELD_VALID)) {
> - if (!i) {
> - snd_printd(KERN_INFO
> - "HDMI: invalid ELD data\n");
> - ret = -EINVAL;
> - goto error;
> - }
> snd_printd(KERN_INFO
> "HDMI: invalid ELD data byte %d\n", i);
> - val = 0;
> - } else
> - val &= AC_ELDD_ELD_DATA;
> + ret = -EINVAL;
> + goto error;
> + }
> + val &= AC_ELDD_ELD_DATA;
> + /*
> + * The first byte cannot be zero. This can happen on some DVI
> + * connections. Some Intel chips may also need some 250ms delay
> + * to return non-zero ELD data, even when the graphics driver
> + * correctly writes ELD content before setting ELD_valid bit.
> + */
> + if (!val && !i) {
> + snd_printdd(KERN_INFO "HDMI: 0 ELD data\n");
> + ret = -EINVAL;
> + goto error;
> + }

Shouldn't this zero-check be before the valid-bit check?
Otherwise it'll never reach there.


thanks,

Takashi


\
 
 \ /
  Last update: 2011-11-22 11:43    [W:0.446 / U:0.092 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site