Re: [PATCH v7 06/10] drivers: qcom: rpmh-rsc: allow invalidation of sleep/wake TCS

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On 2018-05-03 16:06, Matthias Kaehlcke wrote:
Hi Matthias,

Hi Lina,

On Wed, May 02, 2018 at 01:37:45PM -0600, Lina Iyer wrote:
Allow sleep and wake commands to be cleared from the respective TCSes,
so that they can be re-populated.

Signed-off-by: Lina Iyer <ilina@xxxxxxxxxxxxxx>
---

Changes in v7:
	- Move bitmap_zero() outside the loop

Changes in v6:
	- remove unnecessary locks around __tcs_invalidate
	- rename function to tcs_invaldiate

Changes in v4:
	- refactored the rphm_rsc_invalidate()
---
drivers/soc/qcom/rpmh-rsc.c | 45 +++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index 4e2144a14c31..42aedf2d80fe 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -104,6 +104,51 @@ static struct tcs_group *get_tcs_of_type(struct rsc_drv *drv, int type)
 	return &drv->tcs[type];
 }

+static int tcs_invalidate(struct rsc_drv *drv, int type)
+{
+	int m;

nit: use tcs_id?

It's an iterator. Hence didn't change this.

+	struct tcs_group *tcs;
+
+	tcs = get_tcs_of_type(drv, type);
+	if (IS_ERR(tcs))
+		return PTR_ERR(tcs);
+
+	spin_lock(&tcs->lock);
+	if (bitmap_empty(tcs->slots, MAX_TCS_SLOTS)) {
+		spin_unlock(&tcs->lock);
+		return 0;
+	}
+
+	for (m = tcs->offset; m < tcs->offset + tcs->num_tcs; m++) {
+		if (!tcs_is_free(drv, m)) {
+			spin_unlock(&tcs->lock);
+			return -EAGAIN;
+		}
+		write_tcs_reg_sync(drv, RSC_DRV_CMD_ENABLE, m, 0);
+	}
+	bitmap_zero(tcs->slots, MAX_TCS_SLOTS);

You didn't reply to (or address) my comment on v6:

It could occur that one or more TCSes are disabled, then tcs_is_free()
returns false for the next TCS and the function returns without having
updated tcs->slots for the TCSes that have been disabled.
How do you mean TCS are disabled? I think I asked that question in my mail. Sorry, if I forgot to ask.

TCSes are either available for sending requests or they are busy sending requests. They cannot be disabled if they are present. Individual commands, however are enabled or disabled based on whether they have active requests or not.

What we are trying to do here is to cleanup the TCSes of their existing requests. Generally, sleep and wake TCSes are not used to send active state requests, they are sent through AMC/Active TCS. So they will be free. However, in the case of the Display RSC, there is no explicit TCS available for sending active state requests. So we overload the wake TCS to send the active state requests. Even in that case, TCS would have finished and should be free when this function is called. The tcs_is_free() check is addition to make sure the requirement is not violated.

Hope that clears it up.

Thanks,
Lina

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