remoteproc/mtk_scp: Move clk ops outside send_lock

Clocks are properly reference counted and do not need to be inside the
lock range.

Right now this triggers a false-positive lockdep warning on MT8192 based
Chromebooks, through a combination of mtk-scp that has a cros-ec-rpmsg
sub-device, the (actual) cros-ec I2C adapter registration, I2C client
(not on cros-ec) probe doing i2c transfers and enabling clocks.

This is a false positive because the cros-ec-rpmsg under mtk-scp does
not have an I2C adapter, and also each I2C adapter and cros-ec instance
have their own mutex.

Move the clk operations outside of the send_lock range.

Fixes: 63c13d61eafe ("remoteproc/mediatek: add SCP support for mt8183")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230104083110.736377-1-wenst@chromium.org
[Fixed "Fixes:" tag line]
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

diff --git a/drivers/remoteproc/mtk_scp_ipi.c b/drivers/remoteproc/mtk_scp_ipi.c
index 00f041e..4c0d121 100644 (file)
--- a/drivers/remoteproc/mtk_scp_ipi.c
+++ b/drivers/remoteproc/mtk_scp_ipi.c
@@ -164,21 +164,21 @@ int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
            WARN_ON(len > sizeof(send_obj->share_buf)) || WARN_ON(!buf))
                return -EINVAL;
 
-       mutex_lock(&scp->send_lock);
-
        ret = clk_prepare_enable(scp->clk);
        if (ret) {
                dev_err(scp->dev, "failed to enable clock\n");
-               goto unlock_mutex;
+               return ret;
        }
 
+       mutex_lock(&scp->send_lock);
+
         /* Wait until SCP receives the last command */
        timeout = jiffies + msecs_to_jiffies(2000);
        do {
                if (time_after(jiffies, timeout)) {
                        dev_err(scp->dev, "%s: IPI timeout!\n", __func__);
                        ret = -ETIMEDOUT;
-                       goto clock_disable;
+                       goto unlock_mutex;
                }
        } while (readl(scp->reg_base + scp->data->host_to_scp_reg));
 
@@ -205,10 +205,9 @@ int scp_ipi_send(struct mtk_scp *scp, u32 id, void *buf, unsigned int len,
                        ret = 0;
        }
 
-clock_disable:
-       clk_disable_unprepare(scp->clk);
 unlock_mutex:
        mutex_unlock(&scp->send_lock);
+       clk_disable_unprepare(scp->clk);
 
        return ret;
 }