drivers: espi: espi_mchp_xec: Fix the VW change check time

Adjusted the VW change check timings:
- Polling time changed from 100 uSec to 1 uSec.
- Timeout value changed from 10 mSec to 1 mSec.

This is to achieve the lowest possible pulse width for SCI VW in S0,
while ensuring that the VW change check is still reliable for S0iX
where SoC may take longer to process upstream events.

Also added -ETIMEDOUT error when failure.

Signed-off-by: Aditya Bhutada <aditya.bhutada@intel.com>

Author: AdiIntel

drivers/espi/espi_mchp_xec.c

@@ -19,9 +19,9 @@
 #define ESPI_XEC_VWIRE_ACK_DELAY    10ul
 
 /* Maximum timeout to transmit a virtual wire packet.
- * 10 ms expressed in multiples of 100us
+ * 1 ms expressed in multiples of 1us
  */
-#define ESPI_XEC_VWIRE_SEND_TIMEOUT 100ul
+#define ESPI_XEC_VWIRE_SEND_TIMEOUT 1000ul
 
 #define VW_MAX_GIRQS                2ul
 
@@ -461,10 +461,15 @@ static int espi_xec_send_vwire(const struct device *dev,
 		/* Ensure eSPI virtual wire packet is transmitted
 		 * There is no interrupt, so need to poll register
 		 */
-		uint8_t rd_cnt = ESPI_XEC_VWIRE_SEND_TIMEOUT;
+		uint16_t rd_cnt = ESPI_XEC_VWIRE_SEND_TIMEOUT;
 
 		while (reg->SRC_CHG && rd_cnt--) {
-			k_busy_wait(100);
+			k_busy_wait(1);
+		}
+
+		if (rd_cnt == 0) {
+			LOG_ERR("VW %d send timeout", signal);
+			return -ETIMEDOUT;
 		}
 	}
 

drivers/espi/espi_mchp_xec_v2.c

@@ -25,9 +25,9 @@
 #define ESPI_XEC_VWIRE_ACK_DELAY	10ul
 
 /* Maximum timeout to transmit a virtual wire packet.
- * 10 ms expressed in multiples of 100us
+ * 1 ms expressed in multiples of 1us
  */
-#define ESPI_XEC_VWIRE_SEND_TIMEOUT	100ul
+#define ESPI_XEC_VWIRE_SEND_TIMEOUT	1000ul
 
 #define VW_MAX_GIRQS			2ul
 
@@ -325,10 +325,15 @@ static int espi_xec_send_vwire(const struct device *dev,
 		/* Ensure eSPI virtual wire packet is transmitted
 		 * There is no interrupt, so need to poll register
 		 */
-		uint8_t rd_cnt = ESPI_XEC_VWIRE_SEND_TIMEOUT;
+		uint16_t rd_cnt = ESPI_XEC_VWIRE_SEND_TIMEOUT;
 
 		while (sys_read8(regaddr + SMVW_BI_SRC_CHG) && rd_cnt--) {
-			k_busy_wait(100);
+			k_busy_wait(1);
+		}
+
+		if (rd_cnt == 0) {
+			LOG_ERR("VW %d send timeout", signal);
+			return -ETIMEDOUT;
 		}
 	}