-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Thursday, June 26, 2014 6:55 PM To: Lin, Mengdong Cc: alsa-devel@alsa-project.org Subject: Re: [PATCH v2] ALSA: hda - restore BCLK M/N values when resuming HSW/BDW display controller
At Thu, 26 Jun 2014 18:45:16 +0800, mengdong.lin@intel.com wrote:
From: Mengdong Lin mengdong.lin@intel.com
For Intel Haswell/Broadwell display HD-A controller, the 24MHz HD-A link BCLK is converted from Core Display Clock (CDCLK): BCLK = CDCLK * M / N And there are two registers EM4 and EM5 to program M, N value
respectively.
The EM4/EM5 values will be lost and when the display power well is
disabled.
BIOS programs CDCLK selected by OEM and EM4/EM5, but BIOS has no
idea
about display power well on/off at runtime. So the M/N can be wrong if non-default CDCLK is used when the audio controller resumes, which results in an invalid BCLK and abnormal audio playback rate. So this patch saves and restores valid M/N values on controller
suspend/resume.
And 'struct hda_intel' is defined to contain standard HD-A 'struct azx' and Intel specific fields, as Takashi suggested.
Signed-off-by: Mengdong Lin mengdong.lin@intel.com
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index bb65a124..ff9cacd 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -288,6 +288,24 @@ static char *driver_short_names[] = { [AZX_DRIVER_GENERIC] = "HD-Audio Generic", };
+/* Intel HSW/BDW display HDA controller Extended Mode registers.
- EM4 (M value) and EM5 (N Value) are used to convert CDClk (Core
+Display
- Clock) to 24MHz BCLK: BCLK = CDCLK * M / N
- The values will be lost when the display power well is disabled.
- */
+#define ICH6_REG_EM4 0x100c +#define ICH6_REG_EM5 0x1010
Avoid ICH6 prefix. It's just confusing as these are only for HSW/BDW.
Other than that, looks good to me.
So how about adding these?
+#define HDMI_REG_EM4 0x100c +#define HDMI_REG_EM5 0x1010
#define azx_hdmi_readw(chip, reg) \ ((chip)->ops->reg_readw((chip)->remap_addr + HDMI_REG_##reg))
#define azx_hdmi_writew(chip, reg, value) \ ((chip)->ops->reg_writew(value, (chip)->remap_addr + HDMI_REG_##reg))
static void haswell_save_bclk(struct azx *chip) { struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
hda->bclk_m = azx_hdmi_readw(chip, EM4); hda->bclk_n = azx_hdmi_readw(chip, EM5); }
Or use "intel" instead of "hdmi", indicating it's Intel specific.
Thanks Mengdong