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Subject[PATCH V2 1/4] drivers: qcom: rpmh-rsc: simplify TCS locking
Date
From: "Raju P.L.S.S.S.N" <rplsssn@codeaurora.org>

The tcs->lock was introduced to serialize access with in TCS group. But,
drv->lock is still needed to synchronize core aspects of the
communication. This puts the drv->lock in the critical and high latency
path of sending a request. drv->lock provides the all necessary
synchronization. So remove locking around TCS group and simply use the
drv->lock instead.

Signed-off-by: Raju P.L.S.S.S.N <rplsssn@codeaurora.org>
[ilina: split patch into multiple files, update commit text]
Signed-off-by: Lina Iyer <ilina@codeaurora.org>
---
Changes in v2:
- Split the patches into multiple
- Optimzation to remove reundant TCS access
- Split the rpmh library changes into its own patch
- Remove locks in IRQ handler
- Update commit text
- Remove fixes in commit text
---
drivers/soc/qcom/rpmh-internal.h | 2 --
drivers/soc/qcom/rpmh-rsc.c | 32 ++++++++++++--------------------
2 files changed, 12 insertions(+), 22 deletions(-)

diff --git a/drivers/soc/qcom/rpmh-internal.h b/drivers/soc/qcom/rpmh-internal.h
index a7bbbb67991c..969d5030860e 100644
--- a/drivers/soc/qcom/rpmh-internal.h
+++ b/drivers/soc/qcom/rpmh-internal.h
@@ -28,7 +28,6 @@ struct rsc_drv;
* @offset: start of the TCS group relative to the TCSes in the RSC
* @num_tcs: number of TCSes in this type
* @ncpt: number of commands in each TCS
- * @lock: lock for synchronizing this TCS writes
* @req: requests that are sent from the TCS
* @cmd_cache: flattened cache of cmds in sleep/wake TCS
* @slots: indicates which of @cmd_addr are occupied
@@ -40,7 +39,6 @@ struct tcs_group {
u32 offset;
int num_tcs;
int ncpt;
- spinlock_t lock;
const struct tcs_request *req[MAX_TCS_PER_TYPE];
u32 *cmd_cache;
DECLARE_BITMAP(slots, MAX_TCS_SLOTS);
diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index e278fc11fe5c..5ede8d6de3ad 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -106,26 +106,26 @@ static int tcs_invalidate(struct rsc_drv *drv, int type)
{
int m;
struct tcs_group *tcs;
+ int ret = 0;

tcs = get_tcs_of_type(drv, type);

- spin_lock(&tcs->lock);
- if (bitmap_empty(tcs->slots, MAX_TCS_SLOTS)) {
- spin_unlock(&tcs->lock);
- return 0;
- }
+ spin_lock(&drv->lock);
+ if (bitmap_empty(tcs->slots, MAX_TCS_SLOTS))
+ goto done_invalidate;

for (m = tcs->offset; m < tcs->offset + tcs->num_tcs; m++) {
if (!tcs_is_free(drv, m)) {
- spin_unlock(&tcs->lock);
- return -EAGAIN;
+ ret = -EAGAIN;
+ goto done_invalidate;
}
write_tcs_reg_sync(drv, RSC_DRV_CMD_ENABLE, m, 0);
write_tcs_reg_sync(drv, RSC_DRV_CMD_WAIT_FOR_CMPL, m, 0);
}
bitmap_zero(tcs->slots, MAX_TCS_SLOTS);
- spin_unlock(&tcs->lock);

+done_invalidate:
+ spin_unlock(&drv->lock);
return 0;
}

@@ -349,41 +349,35 @@ static int tcs_write(struct rsc_drv *drv, const struct tcs_request *msg)
{
struct tcs_group *tcs;
int tcs_id;
- unsigned long flags;
int ret;

tcs = get_tcs_for_msg(drv, msg);
if (IS_ERR(tcs))
return PTR_ERR(tcs);

- spin_lock_irqsave(&tcs->lock, flags);
spin_lock(&drv->lock);
/*
* The h/w does not like if we send a request to the same address,
* when one is already in-flight or being processed.
*/
ret = check_for_req_inflight(drv, tcs, msg);
- if (ret) {
- spin_unlock(&drv->lock);
+ if (ret)
goto done_write;
- }

tcs_id = find_free_tcs(tcs);
if (tcs_id < 0) {
ret = tcs_id;
- spin_unlock(&drv->lock);
goto done_write;
}

tcs->req[tcs_id - tcs->offset] = msg;
set_bit(tcs_id, drv->tcs_in_use);
- spin_unlock(&drv->lock);

__tcs_buffer_write(drv, tcs_id, 0, msg);
__tcs_trigger(drv, tcs_id);

done_write:
- spin_unlock_irqrestore(&tcs->lock, flags);
+ spin_unlock(&drv->lock);
return ret;
}

@@ -481,19 +475,18 @@ static int tcs_ctrl_write(struct rsc_drv *drv, const struct tcs_request *msg)
{
struct tcs_group *tcs;
int tcs_id = 0, cmd_id = 0;
- unsigned long flags;
int ret;

tcs = get_tcs_for_msg(drv, msg);
if (IS_ERR(tcs))
return PTR_ERR(tcs);

- spin_lock_irqsave(&tcs->lock, flags);
+ spin_lock(&drv->lock);
/* find the TCS id and the command in the TCS to write to */
ret = find_slots(tcs, msg, &tcs_id, &cmd_id);
if (!ret)
__tcs_buffer_write(drv, tcs_id, cmd_id, msg);
- spin_unlock_irqrestore(&tcs->lock, flags);
+ spin_unlock(&drv->lock);

return ret;
}
@@ -584,7 +577,6 @@ static int rpmh_probe_tcs_config(struct platform_device *pdev,
tcs->type = tcs_cfg[i].type;
tcs->num_tcs = tcs_cfg[i].n;
tcs->ncpt = ncpt;
- spin_lock_init(&tcs->lock);

if (!tcs->num_tcs || tcs->type == CONTROL_TCS)
continue;
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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