linux-kernel - [PATCH v5 13/13] firmware: arm_scmi: Make smc support atomic sync commands replies

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Date:   Thu, 23 Sep 2021 15:58:02 +0100
From:   Cristian Marussi <cristian.marussi@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     sudeep.holla@....com, james.quinlan@...adcom.com,
        Jonathan.Cameron@...wei.com, f.fainelli@...il.com,
        etienne.carriere@...aro.org, vincent.guittot@...aro.org,
        souvik.chakravarty@....com, peter.hilber@...nsynergy.com,
        igor.skalkin@...nsynergy.com, cristian.marussi@....com
Subject: [PATCH v5 13/13] firmware: arm_scmi: Make smc support atomic sync commands replies

Enable sync_cmds_atomic_replies in the SMC transport descriptor and remove
SMC specific .poll_done callback support since polling is bypassed when
sync_cmds_atomic_replies is set.

Signed-off-by: Cristian Marussi <cristian.marussi@....com>
---
v4 --> v5
- removed RFC tag
- added comment on setting flag
- remove smc_poll_done
---
 drivers/firmware/arm_scmi/smc.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
index 22c573458719..a338c696852d 100644
--- a/drivers/firmware/arm_scmi/smc.c
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -225,14 +225,6 @@ static void smc_mark_txdone(struct scmi_chan_info *cinfo, int ret)
 	smc_channel_lock_release(scmi_info);
 }
 
-static bool
-smc_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer)
-{
-	struct scmi_smc *scmi_info = cinfo->transport_info;
-
-	return shmem_poll_done(scmi_info->shmem, xfer);
-}
-
 static const struct scmi_transport_ops scmi_smc_ops = {
 	.chan_available = smc_chan_available,
 	.chan_setup = smc_chan_setup,
@@ -240,7 +232,6 @@ static const struct scmi_transport_ops scmi_smc_ops = {
 	.send_message = smc_send_message,
 	.mark_txdone = smc_mark_txdone,
 	.fetch_response = smc_fetch_response,
-	.poll_done = smc_poll_done,
 };
 
 const struct scmi_desc scmi_smc_desc = {
@@ -255,4 +246,13 @@ const struct scmi_desc scmi_smc_desc = {
 	 */
 	.atomic_capable = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
 	.atomic_enabled = IS_ENABLED(CONFIG_ARM_SCMI_TRANSPORT_SMC_ATOMIC_ENABLE),
+	/*
+	 * Setting .sync_cmds_atomic_replies to true for SMC assumes that,
+	 * once the SMC instruction has completed successfully, the issued
+	 * SCMI command would have been already fully processed by the SCMI
+	 * platform firmware and so any possible response value expected
+	 * for the issued command will be immmediately ready to be fetched
+	 * from the shared memory area.
+	 */
+	.sync_cmds_atomic_replies = true,
 };
-- 
2.17.1