[RFC PATCH 29/40] soundwire: intel_init: add kernel module parameter to filter out links

Pierre-Louis Bossart
2019-07-25T23:41:51Z

The hardware and ACPI info may report the presence of links that are
not physically enabled (e.g. due to pin-muxing or hardware reworks),
which in turn can result in errors being thrown. This shouldn't be the
case for production devices but will happen a lot on development
devices - even more so when they expose a connector.

Add a module parameter to filter out such links, e.g. adding the
following config to a file in /etc/modprobe.d will select the second
and third links only.

options soundwire_intel_init sdw_link_mask=0x6

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
drivers/soundwire/intel_init.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/soundwire/intel_init.c b/drivers/soundwire/intel_init.c
index 70637a0383d2..6ae8bb13f907 100644
--- a/drivers/soundwire/intel_init.c
+++ b/drivers/soundwire/intel_init.c
@@ -22,6 +22,10 @@
#define SDW_LINK_BASE 0x30000
#define SDW_LINK_SIZE 0x10000

+static int link_mask;
+module_param_named(sdw_link_mask, link_mask, int, 0444);
+MODULE_PARM_DESC(sdw_link_mask, "Intel link mask (one bit per link)");
+
struct sdw_link_data {
struct sdw_intel_link_res res;
struct platform_device *pdev;
@@ -83,6 +87,9 @@ static struct sdw_intel_ctx
caps = ioread32(res->mmio_base + SDW_SHIM_BASE + SDW_SHIM_LCAP);
caps &= GENMASK(2, 0);

+ dev_dbg(&adev->dev, "SoundWire links: BIOS count %d hardware caps %d\n",
+ count, caps);
+
/* Check HW supported vs property value and use min of two */
count = min_t(u8, caps, count);

@@ -111,6 +118,13 @@ static struct sdw_intel_ctx

/* Create SDW Master devices */
for (i = 0; i < count; i++) {
+ if (link_mask && !(link_mask & BIT(i))) {
+ dev_dbg(&adev->dev,
+ "Link %d masked, will not be enabled\n", i);
+ link++;
+ continue;
+ }
+
link->res.irq = res->irq;
link->res.registers = res->mmio_base + SDW_LINK_BASE
+ (SDW_LINK_SIZE * i);
--
2.20.1