[PATCH 14/21] soundwire: amd: Preserve lane control bits in amd_sdw_port_enable()

[Lee Jones]

lane_ctrl_ch_en_reg holds both the channel enable mask
(AMD_DPN_CH_EN_CHMASK) and the lane control field
(AMD_DPN_CH_EN_LCTRL) programmed by amd_sdw_transport_params().  When
enable_ch->enable is false, amd_sdw_port_enable() writes 0 to the entire
register instead of clearing only AMD_DPN_CH_EN_CHMASK, wiping out the
configured lane control bits.

Clear only the AMD_DPN_CH_EN_CHMASK field when disabling port channels.

Fixes: d8f48fbdfd9a ("soundwire: amd: Add support for AMD Manager driver")
Closes: https://sashiko.dev/#/bug/linux-9a1be49a-7c40-47d3-9260-b933e590c90b
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Lee Jones <lee@xxxxxxxxxx>
---
 drivers/soundwire/amd_manager.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/amd_manager.c b/drivers/soundwire/amd_manager.c
index a8220235a2ae..9dfcdde3f2f0 100644
--- a/drivers/soundwire/amd_manager.c
+++ b/drivers/soundwire/amd_manager.c
@@ -706,11 +706,11 @@ static int amd_sdw_port_enable(struct sdw_bus *bus,
 	 * parameters.
 	 */
 	dpn_ch_enable = readl(amd_manager->mmio + lane_ctrl_ch_en_reg);
-	u32p_replace_bits(&dpn_ch_enable, enable_ch->ch_mask, AMD_DPN_CH_EN_CHMASK);
 	if (enable_ch->enable)
-		writel(dpn_ch_enable, amd_manager->mmio + lane_ctrl_ch_en_reg);
+		u32p_replace_bits(&dpn_ch_enable, enable_ch->ch_mask, AMD_DPN_CH_EN_CHMASK);
 	else
-		writel(0, amd_manager->mmio + lane_ctrl_ch_en_reg);
+		u32p_replace_bits(&dpn_ch_enable, 0, AMD_DPN_CH_EN_CHMASK);
+	writel(dpn_ch_enable, amd_manager->mmio + lane_ctrl_ch_en_reg);
 	return 0;
 }
 
-- 
2.56.0.317.g454f8302e1-goog