[PATCH v2 1/2] ALSA: hda: cs35l41: Safety-guard against capped SPI speed

[Aleksandrs Vinarskis]

Some devices with intel-lpss based SPI controllers may have misconfigured
clock divider due to firmware bug. This would result in capped SPI speeds,
which leads to longer DSP firmware loading times.
This safety guards against possible hangs during wake-up by not
initializing the device if lpss was not patched/fixed UEFI was not
installed

Signed-off-by: Aleksandrs Vinarskis <alex.vinarskis@xxxxxxxxx>
---
 sound/pci/hda/cs35l41_hda_property.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/sound/pci/hda/cs35l41_hda_property.c b/sound/pci/hda/cs35l41_hda_property.c
index c9eb70290973..cb305b093311 100644
--- a/sound/pci/hda/cs35l41_hda_property.c
+++ b/sound/pci/hda/cs35l41_hda_property.c
@@ -210,6 +210,19 @@ static int generic_dsd_config(struct cs35l41_hda *cs35l41, struct device *physde
 
 	if (cfg->bus == SPI) {
 		cs35l41->index = id;
+		/*
+		 * Some devices with intel-lpss based SPI controllers may have misconfigured
+		 * clock divider due to firmware bug. This would result in capped SPI speeds,
+		 * which leads to longer DSP firmware loading times.
+		 * Avoid initializing device if lpss was not patched/fixed UEFI was not installed
+		 */
+		spi = to_spi_device(cs35l41->dev);
+		if (spi->max_speed_hz < CS35L41_SPI_MAX_FREQ/2) {
+			dev_err(cs35l41->dev,
+				"SPI's max_speed_hz is capped at %u Hz, will not continue to avoid hanging\n",
+				spi->max_speed_hz);
+			return -EINVAL;
+		}
 		/*
 		 * Manually set the Chip Select for the second amp <cs_gpio_index> in the node.
 		 * This is only supported for systems with 2 amps, since we cannot expand the
@@ -219,8 +232,6 @@ static int generic_dsd_config(struct cs35l41_hda *cs35l41, struct device *physde
 		 * first.
 		 */
 		if (cfg->cs_gpio_index >= 0) {
-			spi = to_spi_device(cs35l41->dev);
-
 			if (cfg->num_amps != 2) {
 				dev_warn(cs35l41->dev,
 					 "Cannot update SPI CS, Number of Amps (%d) != 2\n",
-- 
2.40.1