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soundwire: intel_auxdevice: add kernel parameter for mclk divider

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Add a kernel parameter to work-around discrepancies between hardware
and platform firmware, it's not unusual to see e.g. 38.4MHz listed in
_DSD properties as the SoundWire clock source, but the hardware may be
based on a 19.2 MHz mclk source.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20241004021850.9758-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Pierre-Louis Bossart 2024-10-04 10:18:50 +08:00 committed by Vinod Koul
parent 71b405b184
commit cbcb7edd09
3 changed files with 15 additions and 2 deletions
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1
Documentation/admin-guide/kernel-parameters.rst
View File

@ -159,6 +159,7 @@ is applicable::
SCSI Appropriate SCSI support is enabled. SCSI Appropriate SCSI support is enabled.
A lot of drivers have their options described inside A lot of drivers have their options described inside
the Documentation/scsi/ sub-directory. the Documentation/scsi/ sub-directory.
SDW SoundWire support is enabled.
SECURITY Different security models are enabled. SECURITY Different security models are enabled.
SELINUX SELinux support is enabled. SELINUX SELinux support is enabled.
SERIAL Serial support is enabled. SERIAL Serial support is enabled.

4
Documentation/admin-guide/kernel-parameters.txt
View File

@ -6060,6 +6060,10 @@
non-zero "wait" parameter. See weight_single non-zero "wait" parameter. See weight_single
and weight_many. and weight_many.
sdw_mclk_divider=[SDW]
Specify the MCLK divider for Intel SoundWire buses in
case the BIOS does not provide the clock rate properly.
skew_tick= [KNL,EARLY] Offset the periodic timer tick per cpu to mitigate skew_tick= [KNL,EARLY] Offset the periodic timer tick per cpu to mitigate
xtime_lock contention on larger systems, and/or RCU lock xtime_lock contention on larger systems, and/or RCU lock
contention on all systems with CONFIG_MAXSMP set. contention on all systems with CONFIG_MAXSMP set.

12
drivers/soundwire/intel_auxdevice.c
View File

@ -41,6 +41,10 @@ static int md_flags;
module_param_named(sdw_md_flags, md_flags, int, 0444); module_param_named(sdw_md_flags, md_flags, int, 0444);
MODULE_PARM_DESC(sdw_md_flags, "SoundWire Intel Master device flags (0x0 all off)"); MODULE_PARM_DESC(sdw_md_flags, "SoundWire Intel Master device flags (0x0 all off)");
static int mclk_divider;
module_param_named(sdw_mclk_divider, mclk_divider, int, 0444);
MODULE_PARM_DESC(sdw_mclk_divider, "SoundWire Intel mclk divider");
struct wake_capable_part { struct wake_capable_part {
const u16 mfg_id; const u16 mfg_id;
const u16 part_id; const u16 part_id;
@ -142,8 +146,12 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
"intel-sdw-ip-clock", "intel-sdw-ip-clock",
&prop->mclk_freq); &prop->mclk_freq);
/* the values reported by BIOS are the 2x clock, not the bus clock */ if (mclk_divider)
prop->mclk_freq /= 2; /* use kernel parameter for BIOS or board work-arounds */
prop->mclk_freq /= mclk_divider;
else
/* the values reported by BIOS are the 2x clock, not the bus clock */
prop->mclk_freq /= 2;
fwnode_property_read_u32(link, fwnode_property_read_u32(link,
"intel-quirk-mask", "intel-quirk-mask",