From cbcb7edd099aee3f001c008fb8bbb1c0d2b7154c Mon Sep 17 00:00:00 2001 From: Pierre-Louis Bossart Date: Fri, 4 Oct 2024 10:18:50 +0800 Subject: [PATCH] soundwire: intel_auxdevice: add kernel parameter for mclk divider 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 Signed-off-by: Bard Liao Link: https://lore.kernel.org/r/20241004021850.9758-1-yung-chuan.liao@linux.intel.com Signed-off-by: Vinod Koul --- Documentation/admin-guide/kernel-parameters.rst | 1 + Documentation/admin-guide/kernel-parameters.txt | 4 ++++ drivers/soundwire/intel_auxdevice.c | 12 ++++++++++-- 3 files changed, 15 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst index fdea7c26ef804..a64130fd19bff 100644 --- a/Documentation/admin-guide/kernel-parameters.rst +++ b/Documentation/admin-guide/kernel-parameters.rst @@ -159,6 +159,7 @@ is applicable:: SCSI Appropriate SCSI support is enabled. A lot of drivers have their options described inside the Documentation/scsi/ sub-directory. + SDW SoundWire support is enabled. SECURITY Different security models are enabled. SELINUX SELinux support is enabled. SERIAL Serial support is enabled. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 1518343bbe223..d7aee9ed5a1d1 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6060,6 +6060,10 @@ non-zero "wait" parameter. See weight_single 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 xtime_lock contention on larger systems, and/or RCU lock contention on all systems with CONFIG_MAXSMP set. diff --git a/drivers/soundwire/intel_auxdevice.c b/drivers/soundwire/intel_auxdevice.c index ae689d5d1ab9e..599954d927529 100644 --- a/drivers/soundwire/intel_auxdevice.c +++ b/drivers/soundwire/intel_auxdevice.c @@ -41,6 +41,10 @@ static int md_flags; module_param_named(sdw_md_flags, md_flags, int, 0444); 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 { const u16 mfg_id; const u16 part_id; @@ -142,8 +146,12 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus) "intel-sdw-ip-clock", &prop->mclk_freq); - /* the values reported by BIOS are the 2x clock, not the bus clock */ - prop->mclk_freq /= 2; + if (mclk_divider) + /* 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, "intel-quirk-mask", -- 2.39.5