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path: root/drivers/firmware/arm_scmi/shmem.c
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Diffstat (limited to 'drivers/firmware/arm_scmi/shmem.c')
-rw-r--r--drivers/firmware/arm_scmi/shmem.c31
1 files changed, 27 insertions, 4 deletions
diff --git a/drivers/firmware/arm_scmi/shmem.c b/drivers/firmware/arm_scmi/shmem.c
index 0e3eaea5d852..1dfe534b8518 100644
--- a/drivers/firmware/arm_scmi/shmem.c
+++ b/drivers/firmware/arm_scmi/shmem.c
@@ -5,10 +5,13 @@
* Copyright (C) 2019 ARM Ltd.
*/
+#include <linux/ktime.h>
#include <linux/io.h>
#include <linux/processor.h>
#include <linux/types.h>
+#include <asm-generic/bug.h>
+
#include "common.h"
/*
@@ -30,16 +33,36 @@ struct scmi_shared_mem {
};
void shmem_tx_prepare(struct scmi_shared_mem __iomem *shmem,
- struct scmi_xfer *xfer)
+ struct scmi_xfer *xfer, struct scmi_chan_info *cinfo)
{
+ ktime_t stop;
+
/*
* Ideally channel must be free by now unless OS timeout last
* request and platform continued to process the same, wait
* until it releases the shared memory, otherwise we may endup
- * overwriting its response with new message payload or vice-versa
+ * overwriting its response with new message payload or vice-versa.
+ * Giving up anyway after twice the expected channel timeout so as
+ * not to bail-out on intermittent issues where the platform is
+ * occasionally a bit slower to answer.
+ *
+ * Note that after a timeout is detected we bail-out and carry on but
+ * the transport functionality is probably permanently compromised:
+ * this is just to ease debugging and avoid complete hangs on boot
+ * due to a misbehaving SCMI firmware.
*/
- spin_until_cond(ioread32(&shmem->channel_status) &
- SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE);
+ stop = ktime_add_ms(ktime_get(), 2 * cinfo->rx_timeout_ms);
+ spin_until_cond((ioread32(&shmem->channel_status) &
+ SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE) ||
+ ktime_after(ktime_get(), stop));
+ if (!(ioread32(&shmem->channel_status) &
+ SCMI_SHMEM_CHAN_STAT_CHANNEL_FREE)) {
+ WARN_ON_ONCE(1);
+ dev_err(cinfo->dev,
+ "Timeout waiting for a free TX channel !\n");
+ return;
+ }
+
/* Mark channel busy + clear error */
iowrite32(0x0, &shmem->channel_status);
iowrite32(xfer->hdr.poll_completion ? 0 : SCMI_SHMEM_FLAG_INTR_ENABLED,