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Subject[RFT PATCH v2 06/10] drivers: qcom: rpmh-rsc: Comment tcs_is_free() + warn if state mismatch
Date
tcs_is_free() had two checks in it: does the software think that the
TCS is free and does the hardware think that the TCS is free. Let's
comment this and also add a warning in the case that software and
hardware disagree, at least for ACTIVE_ONLY TCS.

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

Changes in v2:
- Comment tcs_is_free() new for v2; replaces old patch 6.

drivers/soc/qcom/rpmh-rsc.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
index 9d2669cbd994..93f5d1fb71ca 100644
--- a/drivers/soc/qcom/rpmh-rsc.c
+++ b/drivers/soc/qcom/rpmh-rsc.c
@@ -181,8 +181,27 @@ 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 software thinks it's in use then it's definitely in use */
+ if (test_bit(tcs_id, drv->tcs_in_use))
+ return false;
+
+ /* If hardware agrees it's free then it's definitely free */
+ if (read_tcs_reg(drv, RSC_DRV_STATUS, tcs_id) != 0)
+ return true;
+
+ /*
+ * If we're here then software and hardware disagree about whether
+ * the TCS is free. Software thinks it is free and hardware thinks
+ * it is not.
+ *
+ * Maybe this should be a warning in all cases, but it's almost
+ * certainly a warning for the ACTIVE_TCS where nobody else should
+ * be doing anything else behind our backs. For now we'll just
+ * warn there and then still return that we're in use.
+ */
+ WARN(drv->tcs[tcs_id].type == ACTIVE_TCS,
+ "Driver thought TCS was free but HW reported busy\n");
+ return false;
}

/**
--
2.25.1.481.gfbce0eb801-goog
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