On Tue, Jul 23 2019 at 14:19 -0600, Stephen Boyd wrote:
Quoting Lina Iyer (2019-07-23 12:21:59)
On Tue, Jul 23 2019 at 12:22 -0600, Stephen Boyd wrote:
>Quoting Lina Iyer (2019-07-22 14:53:37)
>> From: "Raju P.L.S.S.S.N" <rplsssn@xxxxxxxxxxxxxx>
>>
>> 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.
>
>This doesn't talk about removing the irq saving and restoring though.
You mean for drv->lock? It was not an _irqsave/_irqrestore anyways and
we were only removing the tcs->lock.
Yes drv->lock wasn't an irqsave/restore variant because it was a
spinlock inside of an obviously already irqsaved region of code because
the tcs->lock was outside the drv->lock and that was saving the irq
flags.
Oh, right.
>Can you keep irq saving and restoring in this patch and then remove that
>in the next patch with reasoning? It probably isn't safe if the lock is
>taken in interrupt context anyway.
>
Yes, the drv->lock should have been irqsave/irqrestore, but it hasn't
been changed by this patch.
It needs to be changed to maintain the irqsaving/restoring of the code.
May be I should club this with the following patch. Instead of adding
irqsave and restore to drv->lock and then remvoing them again in the
following patch.
>> @@ -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);
>>
>
>These ones, just leave them doing the irq save restore for now?
>
drv->lock ??
Yes, it should have irq save/restore still.
