[PATCH v2 10/10] soundwire: intel: don't manage link power individually

From: Bard Liao
Date: Tue Sep 01 2020 - 23:00:33 EST


From: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>

Each link has separate power controls, but experimental results show
we need to use an all-or-none approach to the link power management.

This change has marginal power impacts, the DSP needs to be powered
anyways before SoundWire links can be powered, and even when powered a
link can be in clock-stopped mode.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
drivers/soundwire/intel.c | 70 +++++++++++++++++++++++++--------------
1 file changed, 46 insertions(+), 24 deletions(-)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 97c8cfc54ddd..710f5eba936b 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -63,7 +63,9 @@ MODULE_PARM_DESC(sdw_md_flags, "SoundWire Intel Master device flags (0x0 all off
#define SDW_SHIM_WAKESTS 0x192

#define SDW_SHIM_LCTL_SPA BIT(0)
+#define SDW_SHIM_LCTL_SPA_MASK GENMASK(3, 0)
#define SDW_SHIM_LCTL_CPA BIT(8)
+#define SDW_SHIM_LCTL_CPA_MASK GENMASK(11, 8)

#define SDW_SHIM_SYNC_SYNCPRD_VAL_24 (24000 / SDW_CADENCE_GSYNC_KHZ - 1)
#define SDW_SHIM_SYNC_SYNCPRD_VAL_38_4 (38400 / SDW_CADENCE_GSYNC_KHZ - 1)
@@ -295,8 +297,8 @@ static int intel_link_power_up(struct sdw_intel *sdw)
u32 *shim_mask = sdw->link_res->shim_mask;
struct sdw_bus *bus = &sdw->cdns.bus;
struct sdw_master_prop *prop = &bus->prop;
- int spa_mask, cpa_mask;
- int link_control;
+ u32 spa_mask, cpa_mask;
+ u32 link_control;
int ret = 0;
u32 syncprd;
u32 sync_reg;
@@ -319,6 +321,8 @@ static int intel_link_power_up(struct sdw_intel *sdw)
syncprd = SDW_SHIM_SYNC_SYNCPRD_VAL_24;

if (!*shim_mask) {
+ dev_dbg(sdw->cdns.dev, "%s: powering up all links\n", __func__);
+
/* we first need to program the SyncPRD/CPU registers */
dev_dbg(sdw->cdns.dev,
"%s: first link up, programming SYNCPRD\n", __func__);
@@ -331,21 +335,24 @@ static int intel_link_power_up(struct sdw_intel *sdw)
/* Set SyncCPU bit */
sync_reg |= SDW_SHIM_SYNC_SYNCCPU;
intel_writel(shim, SDW_SHIM_SYNC, sync_reg);
- }

- /* Link power up sequence */
- link_control = intel_readl(shim, SDW_SHIM_LCTL);
- spa_mask = (SDW_SHIM_LCTL_SPA << link_id);
- cpa_mask = (SDW_SHIM_LCTL_CPA << link_id);
- link_control |= spa_mask;
+ /* Link power up sequence */
+ link_control = intel_readl(shim, SDW_SHIM_LCTL);

- ret = intel_set_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask);
- if (ret < 0) {
- dev_err(sdw->cdns.dev, "Failed to power up link: %d\n", ret);
- goto out;
- }
+ /* only power-up enabled links */
+ spa_mask = sdw->link_res->link_mask <<
+ SDW_REG_SHIFT(SDW_SHIM_LCTL_SPA_MASK);
+ cpa_mask = sdw->link_res->link_mask <<
+ SDW_REG_SHIFT(SDW_SHIM_LCTL_CPA_MASK);
+
+ link_control |= spa_mask;
+
+ ret = intel_set_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask);
+ if (ret < 0) {
+ dev_err(sdw->cdns.dev, "Failed to power up link: %d\n", ret);
+ goto out;
+ }

- if (!*shim_mask) {
/* SyncCPU will change once link is active */
ret = intel_wait_bit(shim, SDW_SHIM_SYNC,
SDW_SHIM_SYNC_SYNCCPU, 0);
@@ -483,7 +490,7 @@ static void intel_shim_wake(struct sdw_intel *sdw, bool wake_enable)

static int intel_link_power_down(struct sdw_intel *sdw)
{
- int link_control, spa_mask, cpa_mask;
+ u32 link_control, spa_mask, cpa_mask;
unsigned int link_id = sdw->instance;
void __iomem *shim = sdw->link_res->shim;
u32 *shim_mask = sdw->link_res->shim_mask;
@@ -493,24 +500,39 @@ static int intel_link_power_down(struct sdw_intel *sdw)

intel_shim_master_ip_to_glue(sdw);

- /* Link power down sequence */
- link_control = intel_readl(shim, SDW_SHIM_LCTL);
- spa_mask = ~(SDW_SHIM_LCTL_SPA << link_id);
- cpa_mask = (SDW_SHIM_LCTL_CPA << link_id);
- link_control &= spa_mask;
-
- ret = intel_clear_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask);
-
if (!(*shim_mask & BIT(link_id)))
dev_err(sdw->cdns.dev,
"%s: Unbalanced power-up/down calls\n", __func__);

*shim_mask &= ~BIT(link_id);

+ if (!*shim_mask) {
+
+ dev_dbg(sdw->cdns.dev, "%s: powering down all links\n", __func__);
+
+ /* Link power down sequence */
+ link_control = intel_readl(shim, SDW_SHIM_LCTL);
+
+ /* only power-down enabled links */
+ spa_mask = (~sdw->link_res->link_mask) <<
+ SDW_REG_SHIFT(SDW_SHIM_LCTL_SPA_MASK);
+ cpa_mask = sdw->link_res->link_mask <<
+ SDW_REG_SHIFT(SDW_SHIM_LCTL_CPA_MASK);
+
+ link_control &= spa_mask;
+
+ ret = intel_clear_bit(shim, SDW_SHIM_LCTL, link_control, cpa_mask);
+ }
+
+ link_control = intel_readl(shim, SDW_SHIM_LCTL);
+
mutex_unlock(sdw->link_res->shim_lock);

- if (ret < 0)
+ if (ret < 0) {
+ dev_err(sdw->cdns.dev, "%s: could not power down link\n", __func__);
+
return ret;
+ }

sdw->cdns.link_up = false;
return 0;
--
2.17.1