coresight: tmc: fix failure to disable/enable ETF after reading

ETF may fail to re-enable after reading, and driver->reading will
not be set to false, this will cause failure to enable/disable to ETF.
This change set driver->reading to false even if re-enabling fail.

Fixes: 669c461 ("coresight: tmc: Don't enable TMC when it's not ready.")
Co-developed-by: Yuanfang Zhang <[email protected]>
Signed-off-by: Yuanfang Zhang <[email protected]>
Signed-off-by: Mao Jinlong <[email protected]>
[ Added a comment to explain why we ignore the error ]
Signed-off-by: Suzuki K Poulose <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Mao Jinlong

drivers/hwtracing/coresight/coresight-tmc-etf.c

@@ -756,7 +756,6 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
 	char *buf = NULL;
 	enum tmc_mode mode;
 	unsigned long flags;
-	int rc = 0;
 
 	/* config types are set a boot time and never change */
 	if (WARN_ON_ONCE(drvdata->config_type != TMC_CONFIG_TYPE_ETB &&
@@ -782,11 +781,11 @@ int tmc_read_unprepare_etb(struct tmc_drvdata *drvdata)
 		 * can't be NULL.
 		 */
 		memset(drvdata->buf, 0, drvdata->size);
-		rc = __tmc_etb_enable_hw(drvdata);
-		if (rc) {
-			raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
-			return rc;
-		}
+		/*
+		 * Ignore failures to enable the TMC to make sure, we don't
+		 * leave the TMC in a "reading" state.
+		 */
+		__tmc_etb_enable_hw(drvdata);
 	} else {
 		/*
 		 * The ETB/ETF is not tracing and the buffer was just read.