firmware: arm_scmi: Add missing Rx size re-initialisation

Few commands provide the list of description partially and require
to be called consecutively until all the descriptors are fetched
completely. In such cases, we don't release the buffers and reuse
them for consecutive transmits.

However, currently we don't reset the Rx size which will be set as
per the response for the last transmit. This may result in incorrect
response size being interpretted as the firmware may repond with size
greater than the one set but we read only upto the size set by previous
response.

Let us reset the receive buffer size to max possible in such cases as
we don't know the exact size of the response.

Link:  https://lore.kernel.org/r/20201012141746.32575-1-sudeep.holla@arm.com
Fixes: b6f20ff ("firmware: arm_scmi: add common infrastructure and support for base protocol")
Reported-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

drivers/firmware/arm_scmi/base.c

@@ -197,6 +197,8 @@ static int scmi_base_implementation_list_get(const struct scmi_handle *handle,
 			protocols_imp[tot_num_ret + loop] = *(list + loop);
 
 		tot_num_ret += loop_num_ret;
+
+		scmi_reset_rx_to_maxsz(handle, t);
 	} while (loop_num_ret);
 
 	scmi_xfer_put(handle, t);

drivers/firmware/arm_scmi/clock.c

@@ -192,6 +192,8 @@ scmi_clock_describe_rates_get(const struct scmi_handle *handle, u32 clk_id,
 		}
 
 		tot_rate_cnt += num_returned;
+
+		scmi_reset_rx_to_maxsz(handle, t);
 		/*
 		 * check for both returned and remaining to avoid infinite
 		 * loop due to buggy firmware

drivers/firmware/arm_scmi/common.h

@@ -147,6 +147,8 @@ int scmi_do_xfer_with_response(const struct scmi_handle *h,
 			       struct scmi_xfer *xfer);
 int scmi_xfer_get_init(const struct scmi_handle *h, u8 msg_id, u8 prot_id,
 		       size_t tx_size, size_t rx_size, struct scmi_xfer **p);
+void scmi_reset_rx_to_maxsz(const struct scmi_handle *handle,
+			    struct scmi_xfer *xfer);
 int scmi_handle_put(const struct scmi_handle *handle);
 struct scmi_handle *scmi_handle_get(struct device *dev);
 void scmi_set_handle(struct scmi_device *scmi_dev);

drivers/firmware/arm_scmi/driver.c

@@ -402,6 +402,14 @@ int scmi_do_xfer(const struct scmi_handle *handle, struct scmi_xfer *xfer)
 	return ret;
 }
 
+void scmi_reset_rx_to_maxsz(const struct scmi_handle *handle,
+			    struct scmi_xfer *xfer)
+{
+	struct scmi_info *info = handle_to_scmi_info(handle);
+
+	xfer->rx.len = info->desc->max_msg_size;
+}
+
 #define SCMI_MAX_RESPONSE_TIMEOUT	(2 * MSEC_PER_SEC)
 
 /**

drivers/firmware/arm_scmi/perf.c

@@ -304,6 +304,8 @@ scmi_perf_describe_levels_get(const struct scmi_handle *handle, u32 domain,
 		}
 
 		tot_opp_cnt += num_returned;
+
+		scmi_reset_rx_to_maxsz(handle, t);
 		/*
 		 * check for both returned and remaining to avoid infinite
 		 * loop due to buggy firmware

drivers/firmware/arm_scmi/sensors.c

@@ -166,6 +166,8 @@ static int scmi_sensor_description_get(const struct scmi_handle *handle,
 		}
 
 		desc_index += num_returned;
+
+		scmi_reset_rx_to_maxsz(handle, t);
 		/*
 		 * check for both returned and remaining to avoid infinite
 		 * loop due to buggy firmware