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From: Douglas Anderson <dianders@chromium.org>
To: Andy Gross <agross@kernel.org>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	Maulik Shah <mkshah@codeaurora.org>
Cc: Rajendra Nayak <rnayak@codeaurora.org>,
	mka@chromium.org, evgreen@chromium.org, swboyd@chromium.org,
	Lina Iyer <ilina@codeaurora.org>,
	Douglas Anderson <dianders@chromium.org>,
	linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [RFT PATCH 6/9] drivers: qcom: rpmh-rsc: Only use "tcs_in_use" for ACTIVE_ONLY
Date: Fri,  6 Mar 2020 15:59:48 -0800	[thread overview]
Message-ID: <20200306155707.RFT.6.Icf2213131ea652087f100129359052c83601f8b0@changeid> (raw)
In-Reply-To: <20200306235951.214678-1-dianders@chromium.org>

From trawling through the code (see the "A lot of comments" change) I
found that "tcs_in_use" was only kept up-to-date for ACTIVE_ONLY TCSs.
...yet tcs_is_free() was checking the variable called from
tcs_invalidate() and tcs_invalidate() is only used for non-ACTIVE_ONLY
TCSs.

Let's change tcs_invalidate() to just check the "RSC_DRV_STATUS"
register, which was presumably the important part.

It also feels like for ACTIVE_ONLY TCSs that it probably wasn't
important to check the "RSC_DRV_STATUS".  We'll keep doing it just in
case but we'll add a warning if it ever actually mattered.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

 drivers/soc/qcom/rpmh-rsc.c | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index 190226151029..c63441182358 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -164,7 +164,7 @@ static void write_tcs_reg_sync(struct rsc_drv *drv, int reg, int tcs_id,
 }
 
 /**
- * tcs_is_free() - Return if a TCS is totally free.
+ * tcs_is_free() - Return if an ACTIVE_ONLY TCS is totally free.
  * @drv:    The RSC controller.
  * @tcs_id: The global ID of this TCS.
  *
@@ -177,8 +177,23 @@ static void write_tcs_reg_sync(struct rsc_drv *drv, int reg, int tcs_id,
  */
 static bool tcs_is_free(struct rsc_drv *drv, int tcs_id)
 {
-	return !test_bit(tcs_id, drv->tcs_in_use) &&
-	       read_tcs_reg(drv, RSC_DRV_STATUS, tcs_id);
+	if (test_bit(tcs_id, drv->tcs_in_use))
+		return false;
+
+	if (read_tcs_reg(drv, RSC_DRV_STATUS, tcs_id) != 0)
+		return true;
+
+	/*
+	 * If this warning never ever hits then we can change this function
+	 * to just look at "tcs_in_use" and skip the read of the
+	 * RSC_DRV_STATUS register.
+	 *
+	 * If this warning _does_ hit, we should figure out if this is just
+	 * the way the hardware works or if there is some bug being pointed
+	 * out.
+	 */
+	WARN(1, "Driver thought TCS was free but HW reported busy\n");
+	return false;
 }
 
 /**
@@ -204,7 +219,7 @@ static int tcs_invalidate(struct rsc_drv *drv, int type)
 	}
 
 	for (m = tcs->offset; m < tcs->offset + tcs->num_tcs; m++) {
-		if (!tcs_is_free(drv, m)) {
+		if (read_tcs_reg(drv, RSC_DRV_STATUS, m) == 0) {
 			spin_unlock(&tcs->lock);
 			return -EAGAIN;
 		}
-- 
2.25.1.481.gfbce0eb801-goog


  parent reply	other threads:[~2020-03-07  0:00 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06 23:59 [RFT PATCH 0/9] drivers: qcom: rpmh-rsc: Cleanup / add lots of comments Douglas Anderson
2020-03-06 23:59 ` [RFT PATCH 1/9] drivers: qcom: rpmh-rsc: Clean code reading/writing regs/cmds Douglas Anderson
2020-03-11  8:47   ` Maulik Shah
2020-03-11 15:03     ` Doug Anderson
2020-03-11 16:17       ` Matthias Kaehlcke
2020-03-11 19:30         ` Stephen Boyd
2020-03-06 23:59 ` [RFT PATCH 2/9] drivers: qcom: rpmh-rsc: Document the register layout better Douglas Anderson
2020-03-11  9:35   ` Maulik Shah
2020-03-11 15:27     ` Doug Anderson
2020-03-11 18:49       ` Evan Green
2020-03-11 20:08       ` Stephen Boyd
2020-03-11 22:35         ` Doug Anderson
2020-03-06 23:59 ` [RFT PATCH 3/9] drivers: qcom: rpmh-rsc: Fold tcs_ctrl_write() into its single caller Douglas Anderson
2020-03-11  9:50   ` Maulik Shah
2020-03-06 23:59 ` [RFT PATCH 4/9] drivers: qcom: rpmh-rsc: Remove get_tcs_of_type() abstraction Douglas Anderson
2020-03-11 12:02   ` Maulik Shah
2020-03-06 23:59 ` [RFT PATCH 5/9] drivers: qcom: rpmh-rsc: A lot of comments Douglas Anderson
2020-03-06 23:59 ` Douglas Anderson [this message]
2020-03-11  0:33   ` [RFT PATCH 6/9] drivers: qcom: rpmh-rsc: Only use "tcs_in_use" for ACTIVE_ONLY Doug Anderson
2020-03-06 23:59 ` [RFT PATCH 7/9] drivers: qcom: rpmh-rsc: Warning if tcs_write() used for non-active Douglas Anderson
2020-03-06 23:59 ` [RFT PATCH 8/9] drivers: qcom: rpmh-rsc: spin_lock_irqsave() for tcs_invalidate() Douglas Anderson
2020-03-06 23:59 ` [RFT PATCH 9/9] drivers: qcom: rpmh-rsc: Kill cmd_cache and find_match() with fire Douglas Anderson
2020-03-11  0:35   ` Doug Anderson
2020-03-11  9:48 ` [RFT PATCH 0/9] drivers: qcom: rpmh-rsc: Cleanup / add lots of comments Maulik Shah

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