diff options
Diffstat (limited to 'drivers/firmware/arm_scmi/shmem.c')
| -rw-r--r-- | drivers/firmware/arm_scmi/shmem.c | 31 |
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, |