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ALSA: hda - fail ELD reading early
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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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
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Wu Fengguang authored and Takashi Iwai committed Nov 22, 2011
1 parent a298785 commit a370fc6
Showing 1 changed file with 19 additions and 9 deletions.
28 changes: 19 additions & 9 deletions sound/pci/hda/hda_eld.c
Original file line number Diff line number Diff line change
Expand Up @@ -347,18 +347,28 @@ int snd_hdmi_get_eld(struct hdmi_eld *eld,

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;
}
buf[i] = val;
}

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