[PATCH] ARM: PL330: Fix driver freeze
Jassi Brar
jaswinder.singh at linaro.org
Fri Dec 16 01:27:49 EST 2011
On 12 December 2011 00:57, Javi Merino <javi.merino at arm.com> wrote:
> Add a req_running field to the pl330_thread to track which request (if
> any) has been submitted to the DMA. This mechanism replaces the old
> one in which we tried to guess the same by looking at the PC of the
> DMA, which could prevent the driver from sending more requests if it
> didn't guess correctly.
>
> Signed-off-by: Javi Merino <javi.merino at arm.com>
> Cc: Jassi Brar <jaswinder.singh at linaro.org>
> ---
> arch/arm/common/pl330.c | 116 ++++++++++++++++++++---------------------------
> 1 files changed, 49 insertions(+), 67 deletions(-)
>
> diff --git a/arch/arm/common/pl330.c b/arch/arm/common/pl330.c
> index f407a6b..8d8df74 100644
> --- a/arch/arm/common/pl330.c
> +++ b/arch/arm/common/pl330.c
> @@ -221,17 +221,6 @@
> */
> #define MCODE_BUFF_PER_REQ 256
>
> -/*
> - * Mark a _pl330_req as free.
> - * We do it by writing DMAEND as the first instruction
> - * because no valid request is going to have DMAEND as
> - * its first instruction to execute.
> - */
> -#define MARK_FREE(req) do { \
> - _emit_END(0, (req)->mc_cpu); \
> - (req)->mc_len = 0; \
> - } while (0)
> -
> /* If the _pl330_req is available to the client */
> #define IS_FREE(req) (*((u8 *)((req)->mc_cpu)) == CMD_DMAEND)
>
> @@ -301,8 +290,10 @@ struct pl330_thread {
> struct pl330_dmac *dmac;
> /* Only two at a time */
> struct _pl330_req req[2];
> - /* Index of the last submitted request */
> + /* Index of the last enqueued request */
> unsigned lstenq;
> + /* Index of the last submitted request or -1 if the DMA is stopped */
> + int req_running;
> };
>
> enum pl330_dmac_state {
> @@ -778,6 +769,22 @@ static inline void _execute_DBGINSN(struct pl330_thread *thrd,
> writel(0, regs + DBGCMD);
> }
>
> +/*
> + * Mark a _pl330_req as free.
> + * We do it by writing DMAEND as the first instruction
> + * because no valid request is going to have DMAEND as
> + * its first instruction to execute.
> + */
> +static void mark_free(struct pl330_thread *thrd, int idx)
> +{
> + struct _pl330_req *req = &thrd->req[idx];
> +
> + _emit_END(0, req->mc_cpu);
> + req->mc_len = 0;
> +
> + thrd->req_running = -1;
> +}
> +
> static inline u32 _state(struct pl330_thread *thrd)
> {
> void __iomem *regs = thrd->dmac->pinfo->base;
> @@ -836,31 +843,6 @@ static inline u32 _state(struct pl330_thread *thrd)
> }
> }
>
> -/* If the request 'req' of thread 'thrd' is currently active */
> -static inline bool _req_active(struct pl330_thread *thrd,
> - struct _pl330_req *req)
> -{
> - void __iomem *regs = thrd->dmac->pinfo->base;
> - u32 buf = req->mc_bus, pc = readl(regs + CPC(thrd->id));
> -
> - if (IS_FREE(req))
> - return false;
> -
> - return (pc >= buf && pc <= buf + req->mc_len) ? true : false;
> -}
> -
> -/* Returns 0 if the thread is inactive, ID of active req + 1 otherwise */
> -static inline unsigned _thrd_active(struct pl330_thread *thrd)
> -{
> - if (_req_active(thrd, &thrd->req[0]))
> - return 1; /* First req active */
> -
> - if (_req_active(thrd, &thrd->req[1]))
> - return 2; /* Second req active */
> -
> - return 0;
> -}
> -
> static void _stop(struct pl330_thread *thrd)
> {
> void __iomem *regs = thrd->dmac->pinfo->base;
> @@ -892,17 +874,22 @@ static bool _trigger(struct pl330_thread *thrd)
> struct _arg_GO go;
> unsigned ns;
> u8 insn[6] = {0, 0, 0, 0, 0, 0};
> + int idx;
>
> /* Return if already ACTIVE */
> if (_state(thrd) != PL330_STATE_STOPPED)
> return true;
>
> - if (!IS_FREE(&thrd->req[1 - thrd->lstenq]))
> - req = &thrd->req[1 - thrd->lstenq];
> - else if (!IS_FREE(&thrd->req[thrd->lstenq]))
> - req = &thrd->req[thrd->lstenq];
> - else
> - req = NULL;
> + idx = 1 - thrd->lstenq;
> + if (!IS_FREE(&thrd->req[idx]))
> + req = &thrd->req[idx];
> + else {
> + idx = thrd->lstenq;
> + if (!IS_FREE(&thrd->req[idx]))
> + req = &thrd->req[idx];
> + else
> + req = NULL;
> + }
>
> /* Return if no request */
> if (!req || !req->r)
> @@ -933,6 +920,8 @@ static bool _trigger(struct pl330_thread *thrd)
> /* Only manager can execute GO */
> _execute_DBGINSN(thrd, insn, true);
>
> + thrd->req_running = idx;
> +
> return true;
> }
>
> @@ -1382,8 +1371,8 @@ static void pl330_dotask(unsigned long data)
>
> thrd->req[0].r = NULL;
> thrd->req[1].r = NULL;
> - MARK_FREE(&thrd->req[0]);
> - MARK_FREE(&thrd->req[1]);
> + mark_free(thrd, 0);
> + mark_free(thrd, 1);
>
> /* Clear the reset flag */
> pl330->dmac_tbd.reset_chan &= ~(1 << i);
> @@ -1461,14 +1450,12 @@ int pl330_update(const struct pl330_info *pi)
>
> thrd = &pl330->channels[id];
>
> - active = _thrd_active(thrd);
> - if (!active) /* Aborted */
> + active = thrd->req_running;
> + if (active == -1) /* Aborted */
> continue;
>
> - active -= 1;
> -
> rqdone = &thrd->req[active];
> - MARK_FREE(rqdone);
> + mark_free(thrd, active);
>
> /* Get going again ASAP */
> _start(thrd);
> @@ -1509,7 +1496,7 @@ int pl330_chan_ctrl(void *ch_id, enum pl330_chan_op op)
> struct pl330_thread *thrd = ch_id;
> struct pl330_dmac *pl330;
> unsigned long flags;
> - int ret = 0, active;
> + int ret = 0, active = thrd->req_running;
>
> if (!thrd || thrd->free || thrd->dmac->state == DYING)
> return -EINVAL;
> @@ -1525,28 +1512,24 @@ int pl330_chan_ctrl(void *ch_id, enum pl330_chan_op op)
>
> thrd->req[0].r = NULL;
> thrd->req[1].r = NULL;
> - MARK_FREE(&thrd->req[0]);
> - MARK_FREE(&thrd->req[1]);
> + mark_free(thrd, 0);
> + mark_free(thrd, 1);
> break;
>
> case PL330_OP_ABORT:
> - active = _thrd_active(thrd);
> -
> /* Make sure the channel is stopped */
> _stop(thrd);
>
> /* ABORT is only for the active req */
> - if (!active)
> + if (active == -1)
> break;
>
> - active--;
> -
> thrd->req[active].r = NULL;
> - MARK_FREE(&thrd->req[active]);
> + mark_free(thrd, active);
>
> /* Start the next */
> case PL330_OP_START:
> - if (!_thrd_active(thrd) && !_start(thrd))
> + if ((active == -1) && !_start(thrd))
> ret = -EIO;
> break;
>
> @@ -1587,14 +1570,13 @@ int pl330_chan_status(void *ch_id, struct pl330_chanstatus *pstatus)
> else
> pstatus->faulting = false;
>
> - active = _thrd_active(thrd);
> + active = thrd->req_running;
>
> - if (!active) {
> + if (active == -1) {
> /* Indicate that the thread is not running */
> pstatus->top_req = NULL;
> pstatus->wait_req = NULL;
> } else {
> - active--;
> pstatus->top_req = thrd->req[active].r;
> pstatus->wait_req = !IS_FREE(&thrd->req[1 - active])
> ? thrd->req[1 - active].r : NULL;
> @@ -1659,9 +1641,9 @@ void *pl330_request_channel(const struct pl330_info *pi)
> thrd->free = false;
> thrd->lstenq = 1;
> thrd->req[0].r = NULL;
> - MARK_FREE(&thrd->req[0]);
> + mark_free(thrd, 0);
> thrd->req[1].r = NULL;
> - MARK_FREE(&thrd->req[1]);
> + mark_free(thrd, 1);
> break;
> }
> }
> @@ -1767,14 +1749,14 @@ static inline void _reset_thread(struct pl330_thread *thrd)
> thrd->req[0].mc_bus = pl330->mcode_bus
> + (thrd->id * pi->mcbufsz);
> thrd->req[0].r = NULL;
> - MARK_FREE(&thrd->req[0]);
> + mark_free(thrd, 0);
>
> thrd->req[1].mc_cpu = thrd->req[0].mc_cpu
> + pi->mcbufsz / 2;
> thrd->req[1].mc_bus = thrd->req[0].mc_bus
> + pi->mcbufsz / 2;
> thrd->req[1].r = NULL;
> - MARK_FREE(&thrd->req[1]);
> + mark_free(thrd, 1);
> }
>
> static int dmac_alloc_threads(struct pl330_dmac *pl330)
> --
Seems ok, except that 'unsigned lstenq' and 'int req_running' occupy
real estate more than they should for their purpose. Though otherwise
the necessary helpers would bloat the code too.
Hoping you have done testing of enough corner cases...
Acked-by: Jassi Brar <jaswinder.singh at linaro.org>
Thanks.
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