Re: [RESEND PATCH v1 2/2] Revert "mailbox: mediatek: remove implementation related to atomic_exec"

[Chun-Kuang Hu <chunkuang.hu@kernel.org>]

Hi, Yongqiang:

Yongqiang Niu <yongqiang.niu@mediatek.com> 於 2021年3月10日 週三 下午6:58寫道：
>
> This reverts commit c9ea564f3d9dd20d88bd34f40a6ff6d31a0d7e8c.
>
> Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
> ---
>  drivers/mailbox/mtk-cmdq-mailbox.c | 80 +++++++++++++++++++++++++++++++++-----
>  1 file changed, 71 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
> index 5665b6e..e0d9a86 100644
> --- a/drivers/mailbox/mtk-cmdq-mailbox.c
> +++ b/drivers/mailbox/mtk-cmdq-mailbox.c
> @@ -56,6 +56,7 @@ struct cmdq_thread {
>         void __iomem            *base;
>         struct list_head        task_busy_list;
>         u32                     priority;
> +       bool                    atomic_exec;
>  };
>
>  struct cmdq_task {
> @@ -168,18 +169,56 @@ static void cmdq_task_insert_into_thread(struct cmdq_task *task)
>         dma_sync_single_for_cpu(dev, prev_task->pa_base,
>                                 prev_task->pkt->cmd_buf_size, DMA_TO_DEVICE);
>         prev_task_base[CMDQ_NUM_CMD(prev_task->pkt) - 1] =
> -               (u64)CMDQ_JUMP_BY_PA << 32 | task->pa_base;
> +               (u64)CMDQ_JUMP_BY_PA << 32 |
> +               (task->pa_base >> task->cmdq->shift_pa);
>         dma_sync_single_for_device(dev, prev_task->pa_base,
>                                    prev_task->pkt->cmd_buf_size, DMA_TO_DEVICE);
>
>         cmdq_thread_invalidate_fetched_data(thread);
>  }
>
> +static bool cmdq_command_is_wfe(u64 cmd)
> +{
> +       u64 wfe_option = CMDQ_WFE_UPDATE | CMDQ_WFE_WAIT | CMDQ_WFE_WAIT_VALUE;
> +       u64 wfe_op = (u64)(CMDQ_CODE_WFE << CMDQ_OP_CODE_SHIFT) << 32;
> +       u64 wfe_mask = (u64)CMDQ_OP_CODE_MASK << 32 | 0xffffffff;
> +
> +       return ((cmd & wfe_mask) == (wfe_op | wfe_option));
> +}
> +
> +/* we assume tasks in the same display GCE thread are waiting the same event. */
> +static void cmdq_task_remove_wfe(struct cmdq_task *task)
> +{
> +       struct device *dev = task->cmdq->mbox.dev;
> +       u64 *base = task->pkt->va_base;
> +       int i;
> +
> +       dma_sync_single_for_cpu(dev, task->pa_base, task->pkt->cmd_buf_size,
> +                               DMA_TO_DEVICE);
> +       for (i = 0; i < CMDQ_NUM_CMD(task->pkt); i++)
> +               if (cmdq_command_is_wfe(base[i]))
> +                       base[i] = (u64)CMDQ_JUMP_BY_OFFSET << 32 |
> +                                 (CMDQ_JUMP_PASS >> task->cmdq->shift_pa);
> +       dma_sync_single_for_device(dev, task->pa_base, task->pkt->cmd_buf_size,
> +                                  DMA_TO_DEVICE);
> +}
> +
>  static bool cmdq_thread_is_in_wfe(struct cmdq_thread *thread)
>  {
>         return readl(thread->base + CMDQ_THR_WAIT_TOKEN) & CMDQ_THR_IS_WAITING;
>  }
>
> +static void cmdq_thread_wait_end(struct cmdq_thread *thread,
> +                                unsigned long end_pa)
> +{
> +       struct device *dev = thread->chan->mbox->dev;
> +       unsigned long curr_pa;
> +
> +       if (readl_poll_timeout_atomic(thread->base + CMDQ_THR_CURR_ADDR,
> +                       curr_pa, curr_pa == end_pa, 1, 20))
> +               dev_err(dev, "GCE thread cannot run to end.\n");
> +}
> +
>  static void cmdq_task_exec_done(struct cmdq_task *task, enum cmdq_cb_status sta)
>  {
>         struct cmdq_task_cb *cb = &task->pkt->async_cb;
> @@ -371,15 +410,37 @@ static int cmdq_mbox_send_data(struct mbox_chan *chan, void *data)
>                         cmdq->shift_pa;
>                 end_pa = readl(thread->base + CMDQ_THR_END_ADDR) <<
>                         cmdq->shift_pa;
> -               /* check boundary */
> -               if (curr_pa == end_pa - CMDQ_INST_SIZE ||
> -                   curr_pa == end_pa) {
> -                       /* set to this task directly */
> -                       writel(task->pa_base >> cmdq->shift_pa,
> -                              thread->base + CMDQ_THR_CURR_ADDR);
> +
> +               /*
> +                * Atomic execution should remove the following wfe, i.e. only
> +                * wait event at first task, and prevent to pause when running.
> +                */
> +               if (thread->atomic_exec) {
> +                       /* GCE is executing if command is not WFE */
> +                       if (!cmdq_thread_is_in_wfe(thread)) {
> +                               cmdq_thread_resume(thread);
> +                               cmdq_thread_wait_end(thread,
> +                                                    end_pa >> cmdq->shift_pa);
> +                               WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> +                               /* set to this task directly */
> +                               writel(task->pa_base >> cmdq->shift_pa,
> +                                      thread->base + CMDQ_THR_CURR_ADDR);
> +                       } else {
> +                               cmdq_task_insert_into_thread(task);
> +                               cmdq_task_remove_wfe(task);
> +                               smp_mb(); /* modify jump before enable thread */
> +                       }
>                 } else {
> -                       cmdq_task_insert_into_thread(task);
> -                       smp_mb(); /* modify jump before enable thread */
> +                       /* check boundary */
> +                       if (curr_pa == end_pa - CMDQ_INST_SIZE ||
> +                           curr_pa == end_pa) {
> +                               /* set to this task directly */
> +                               writel(task->pa_base >> cmdq->shift_pa,
> +                                      thread->base + CMDQ_THR_CURR_ADDR);
> +                       } else {
> +                               cmdq_task_insert_into_thread(task);
> +                               smp_mb(); /* modify jump before enable thread */
> +                       }
>                 }
>                 writel((task->pa_base + pkt->cmd_buf_size) >> cmdq->shift_pa,
>                        thread->base + CMDQ_THR_END_ADDR);
> @@ -500,6 +561,7 @@ static struct mbox_chan *cmdq_xlate(struct mbox_controller *mbox,
>
>         thread = (struct cmdq_thread *)mbox->chans[ind].con_priv;
>         thread->priority = sp->args[1];
> +       thread->atomic_exec = (sp->args[2] != 0);

This does not match the binding [1].
Why not just fix the bug rather than revert this patch?

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/mailbox/mtk-gce.txt?h=v5.12-rc2

Regards,
Chun-Kuang.

>         thread->chan = &mbox->chans[ind];
>
>         return &mbox->chans[ind];
> --
> 1.8.1.1.dirty
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