linux-kernel - [PATCH] firmware: qcom: scm: Fix interrupted SCM calls fully

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Date:   Wed, 28 Sep 2016 16:12:28 +0530
From:   Sricharan R <sricharan@...eaurora.org>
To:     patches@...aro.org, linux-arm-msm@...r.kernel.org,
        will.deacon@....com, stanimir.varbanov@...aro.org,
        linux-kernel@...r.kernel.org, srinivas.kandagatla@...aro.org,
        catalin.marinas@....com, andy.gross@...aro.org,
        bjorn.andersson@...aro.org, sboyd@...eaurora.org
Cc:     sricharan@...eaurora.org
Subject: [PATCH] firmware: qcom: scm: Fix interrupted SCM calls fully

Patch [1] fixes the issues with interrupted SCM64 calls
by returning the register r6 (Session ID) on the next try, but register
r0 also needs to be preserved for the retry. r0 contains the
result of the previous try. Without this i see that the SCM calls
hang when retried.

[1] https://patchwork.kernel.org/patch/9291589/

Signed-off-by: Sricharan R <sricharan@...eaurora.org>
---
 drivers/firmware/qcom_scm-64.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/qcom_scm-64.c b/drivers/firmware/qcom_scm-64.c
index 7ecd0e7..28b604e 100755
--- a/drivers/firmware/qcom_scm-64.c
+++ b/drivers/firmware/qcom_scm-64.c
@@ -134,6 +134,9 @@ static int qcom_scm_call(struct device *dev, u32 svc_id, u32 cmd_id,
 		res->a6 = 0;
 
 		do {
+			if (res->a0 == QCOM_SCM_INTERRUPTED)
+				cmd = res->a0;
+
 			arm_smccc_smc(cmd, desc->arginfo, desc->args[0],
 				      desc->args[1], desc->args[2], x5, res->a6, 0,
 				      res);
-- 
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