Messages in this thread | | | Date | Tue, 22 Nov 2011 11:39:53 +0100 | From | Takashi Iwai <> | Subject | Re: [alsa-devel] [PATCH] hda - fail ELD reading early |
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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
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