Re: [PATCH v8 2/3] CMDQ: Mediatek CMDQ driver

Horng-Shyang Liao
2016-06-01T09:57:00Z

Hi Mathias,

Please see my inline reply.

On Tue, 2016-05-31 at 22:04 +0200, Matthias Brugger wrote:
>
> On 31/05/16 10:36, Horng-Shyang Liao wrote:
> > Hi Mathias,
> >
> > Please see my inline reply.
> >
> > On Mon, 2016-05-30 at 17:31 +0200, Matthias Brugger wrote:
> >>
> >> On 30/05/16 05:19, HS Liao wrote:
> >>> This patch is first version of Mediatek Command Queue(CMDQ) driver. The
> >>> CMDQ is used to help read/write registers with critical time limitation,
> >>> such as updating display configuration during the vblank. It controls
> >>> Global Command Engine (GCE) hardware to achieve this requirement.
> >>> Currently, CMDQ only supports display related hardwares, but we expect
> >>> it can be extended to other hardwares for future requirements.
> >>>
> >>> Signed-off-by: HS Liao <hs.liao@mediatek.com>
> >>> Signed-off-by: CK Hu <ck.hu@mediatek.com>
> >>> ---
> >>> drivers/soc/mediatek/Kconfig | 10 +
> >>> drivers/soc/mediatek/Makefile | 1 +
> >>> drivers/soc/mediatek/mtk-cmdq.c | 943 ++++++++++++++++++++++++++++++++++++++++
> >>> include/soc/mediatek/cmdq.h | 197 +++++++++
> >>> 4 files changed, 1151 insertions(+)
> >>> create mode 100644 drivers/soc/mediatek/mtk-cmdq.c
> >>> create mode 100644 include/soc/mediatek/cmdq.h
> >>>
> >>> diff --git a/drivers/soc/mediatek/Kconfig b/drivers/soc/mediatek/Kconfig
> >>> index 0a4ea80..c4ad75c 100644
> >>> --- a/drivers/soc/mediatek/Kconfig
> >>> +++ b/drivers/soc/mediatek/Kconfig
> >>> @@ -1,6 +1,16 @@
> >>> #
> >>> # MediaTek SoC drivers
> >>> #
> >>> +config MTK_CMDQ
> >>> + bool "MediaTek CMDQ Support"
> >>> + depends on ARCH_MEDIATEK || COMPILE_TEST
>
> depends on ARM64 ?

Will add ARM64.

> >>> + select MTK_INFRACFG
> >>> + help
> >>> + Say yes here to add support for the MediaTek Command Queue (CMDQ)
> >>> + driver. The CMDQ is used to help read/write registers with critical
> >>> + time limitation, such as updating display configuration during the
> >>> + vblank.
> >>> +
> >>> config MTK_INFRACFG
> >>> bool "MediaTek INFRACFG Support"
> >>> depends on ARCH_MEDIATEK || COMPILE_TEST
> >>> diff --git a/drivers/soc/mediatek/Makefile b/drivers/soc/mediatek/Makefile
> >>> index 12998b0..f7397ef 100644
> >>> --- a/drivers/soc/mediatek/Makefile
> >>> +++ b/drivers/soc/mediatek/Makefile
> >>> @@ -1,3 +1,4 @@
> >>> +obj-$(CONFIG_MTK_CMDQ) += mtk-cmdq.o
> >>> obj-$(CONFIG_MTK_INFRACFG) += mtk-infracfg.o
> >>> obj-$(CONFIG_MTK_PMIC_WRAP) += mtk-pmic-wrap.o
> >>> obj-$(CONFIG_MTK_SCPSYS) += mtk-scpsys.o
> >>> diff --git a/drivers/soc/mediatek/mtk-cmdq.c b/drivers/soc/mediatek/mtk-cmdq.c
> >>> new file mode 100644
> >>> index 0000000..e9d6e1c
> >>> --- /dev/null
> >>> +++ b/drivers/soc/mediatek/mtk-cmdq.c
> >>> @@ -0,0 +1,943 @@
> >>> +/*
> >>> + * Copyright (c) 2015 MediaTek Inc.
> >>> + *
> >>> + * This program is free software; you can redistribute it and/or modify
> >>> + * it under the terms of the GNU General Public License version 2 as
> >>> + * published by the Free Software Foundation.
> >>> + *
> >>> + * This program is distributed in the hope that it will be useful,
> >>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> >>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> >>> + * GNU General Public License for more details.
> >>> + */
> >>> +
> >>> +#include <linux/clk.h>
> >>> +#include <linux/clk-provider.h>
> >>> +#include <linux/completion.h>
> >>> +#include <linux/dma-mapping.h>
> >>> +#include <linux/errno.h>
> >>> +#include <linux/interrupt.h>
> >>> +#include <linux/iopoll.h>
> >>> +#include <linux/kernel.h>
> >>> +#include <linux/kthread.h>
> >>> +#include <linux/module.h>
> >>> +#include <linux/mutex.h>
> >>> +#include <linux/of_address.h>
> >>> +#include <linux/of_irq.h>
> >>> +#include <linux/platform_device.h>
> >>> +#include <linux/slab.h>
> >>> +#include <linux/spinlock.h>
> >>> +#include <linux/suspend.h>
> >>> +#include <linux/workqueue.h>
> >>> +#include <soc/mediatek/cmdq.h>
> >>> +
> >>> +#define CMDQ_INITIAL_CMD_BLOCK_SIZE PAGE_SIZE
> >>> +#define CMDQ_INST_SIZE 8 /* instruction is 64-bit */
> >>> +#define CMDQ_TIMEOUT_MS 1000
> >>> +#define CMDQ_IRQ_MASK 0xffff
> >>> +#define CMDQ_DRIVER_DEVICE_NAME "mtk_cmdq"
> >>> +#define CMDQ_CLK_NAME "gce"
> >>
> >> We can put the names in directly to un-bloat the defines.
> >
> > I will use the names directly and remove defines.
> >
> >>> +
> >>> +#define CMDQ_CURR_IRQ_STATUS 0x010
> >>> +#define CMDQ_CURR_LOADED_THR 0x018
> >>> +#define CMDQ_THR_SLOT_CYCLES 0x030
> >>> +
> >>> +#define CMDQ_THR_BASE 0x100
> >>> +#define CMDQ_THR_SHIFT 0x080
> >>
> >> Wouldn't be CMDQ_THR_SIZE more accurate?
> >
> > Will rename it.
> >
> >>> +#define CMDQ_THR_WARM_RESET 0x00
> >>> +#define CMDQ_THR_ENABLE_TASK 0x04
> >>> +#define CMDQ_THR_SUSPEND_TASK 0x08
> >>> +#define CMDQ_THR_CURR_STATUS 0x0c
> >>> +#define CMDQ_THR_IRQ_STATUS 0x10
> >>> +#define CMDQ_THR_IRQ_ENABLE 0x14
> >>> +#define CMDQ_THR_CURR_ADDR 0x20
> >>> +#define CMDQ_THR_END_ADDR 0x24
> >>> +#define CMDQ_THR_CFG 0x40
> >>> +
> >>> +#define CMDQ_THR_ENABLED 0x1
> >>> +#define CMDQ_THR_DISABLED 0x0
> >>> +#define CMDQ_THR_SUSPEND 0x1
> >>> +#define CMDQ_THR_RESUME 0x0
> >>> +#define CMDQ_THR_STATUS_SUSPENDED BIT(1)
> >>> +#define CMDQ_THR_DO_WARM_RESET BIT(0)
> >>> +#define CMDQ_THR_ACTIVE_SLOT_CYCLES 0x3200
> >>> +#define CMDQ_THR_PRIORITY 3
> >>> +#define CMDQ_THR_IRQ_DONE 0x1
> >>> +#define CMDQ_THR_IRQ_ERROR 0x12
> >>> +#define CMDQ_THR_IRQ_EN 0x13 /* done + error */
> >>
> >> #define CMDQ_THR_IRQ_EN (CMDQ_THR_IRQ_ERROR | CMDQ_THR_IRQ_DONE)
> >
> > Will do.
> >
> >>> +#define CMDQ_THR_IRQ_MASK 0x13
> >>
> >> never used.
> >
> > Will remove.
> >
> >>> +#define CMDQ_THR_EXECUTING BIT(31)
> >>> +
> >>> +#define CMDQ_ARG_A_WRITE_MASK 0xffff
> >>> +#define CMDQ_SUBSYS_MASK 0x1f
> >>> +#define CMDQ_OP_CODE_MASK 0xff000000
> >>> +
> >>> +#define CMDQ_OP_CODE_SHIFT 24
> >>
> >> Couldn't we connect the mask with the shift, or aren't they related?
> >>
> >> #define CMDQ_OP_CODE_MASK (0xff << CMDQ_OP_CODE_SHIFT)
> >
> > Will do.
> >
> >>> +#define CMDQ_SUBSYS_SHIFT 16
> >>> +
> >>> +#define CMDQ_WRITE_ENABLE_MASK BIT(0)
> >>> +#define CMDQ_JUMP_BY_OFFSET 0x10000000
> >>> +#define CMDQ_JUMP_BY_PA 0x10000001
> >>> +#define CMDQ_JUMP_PASS CMDQ_INST_SIZE
> >>> +#define CMDQ_WFE_UPDATE BIT(31)
> >>> +#define CMDQ_WFE_WAIT BIT(15)
> >>> +#define CMDQ_WFE_WAIT_VALUE 0x1
> >>> +#define CMDQ_EOC_IRQ_EN BIT(0)
> >>> +
> >>> +enum cmdq_thread_index {
> >>> + CMDQ_THR_DISP_MAIN_IDX, /* main */
> >>> + CMDQ_THR_DISP_SUB_IDX, /* sub */
> >>> + CMDQ_THR_DISP_MISC_IDX, /* misc */
> >>> + CMDQ_THR_MAX_COUNT, /* max */
> >>> +};
> >>> +
> >>> +/*
> >>> + * CMDQ_CODE_MOVE:
> >>> + * move value into internal register as mask
> >>> + * format: op mask
> >>> + * CMDQ_CODE_WRITE:
> >>> + * write value into target register
> >>> + * format: op subsys address value
> >>> + * CMDQ_CODE_JUMP:
> >>> + * jump by offset
> >>> + * format: op offset
> >>> + * CMDQ_CODE_WFE:
> >>> + * wait for event and clear
> >>> + * it is just clear if no wait
> >>> + * format: [wait] op event update:1 to_wait:1 wait:1
> >>> + * [clear] op event update:1 to_wait:0 wait:0
> >>> + * CMDQ_CODE_EOC:
> >>> + * end of command
> >>> + * format: op irq_flag
> >>> + */
> >>
> >> I think we need more documentation of how this command queue engine is
> >> working. If not, I think it will be really complicated to understand how
> >> to use this.
> >>
> >>> +enum cmdq_code {
> >>> + CMDQ_CODE_MOVE = 0x02,
> >>> + CMDQ_CODE_WRITE = 0x04,
> >>> + CMDQ_CODE_JUMP = 0x10,
> >>> + CMDQ_CODE_WFE = 0x20,
> >>> + CMDQ_CODE_EOC = 0x40,
> >>> +};
> >>> +
> >>> +enum cmdq_task_state {
> >>> + TASK_STATE_BUSY, /* running on a GCE thread */
> >>> + TASK_STATE_ERROR,
> >>> + TASK_STATE_DONE,
> >>> +};
> >>> +
> >>> +struct cmdq_task_cb {
> >>> + cmdq_async_flush_cb cb;
> >>> + void *data;
> >>> +};
> >>> +
> >>> +struct cmdq_thread {
> >>> + void __iomem *base;
> >>> + struct list_head task_busy_list;
> >>> + wait_queue_head_t wait_task_done;
> >>> +};
> >>> +
> >>> +struct cmdq_task {
> >>> + struct cmdq *cmdq;
> >>> + struct list_head list_entry;
> >>> + enum cmdq_task_state task_state;
> >>> + void *va_base;
> >>> + dma_addr_t pa_base;
> >>> + u64 engine_flag;
> >>> + size_t command_size;
> >>> + u32 num_cmd;
> >>
> >> num_cmd is directly connected to command_size. I prefer to just keep
> >> num_cmd and calculate the command_size where necessary.
> >
> > After I trace code, I prefer to keep command_size and calculate num_cmd
> > where necessary. What do you think?
> >
>
> I suppose you prefer this, as you are writing to the GCE depending on
> the command_size. I think it is worth to create a macro for the
> calculation of the number of commands, to make the code more readable.
> Would be nice if you would just pass cmdq_task to it and it would return
> the number. Just as an idea.

Will add macro.

> >>> + struct cmdq_thread *thread;
> >>> + struct cmdq_task_cb cb;
> >>> + struct work_struct release_work;
> >>> +};
> >>> +
> >>> +struct cmdq {
> >>> + struct device *dev;
> >>> + void __iomem *base;
> >>> + u32 irq;
> >>> + struct workqueue_struct *task_release_wq;
> >>> + struct cmdq_thread thread[CMDQ_THR_MAX_COUNT];
> >>> + struct mutex task_mutex; /* for task */
> >>> + spinlock_t exec_lock; /* for exec */
> >>> + struct clk *clock;
> >>> + bool suspended;
> >>> +};
> >>> +
> >>> +struct cmdq_subsys {
> >>> + u32 base;
> >>> + int id;
> >>> +};
> >>> +
> >>> +static const struct cmdq_subsys gce_subsys[] = {
> >>> + {0x1400, 1},
> >>> + {0x1401, 2},
> >>> + {0x1402, 3},
> >>> +};
> >>> +
> >>> +static int cmdq_subsys_base_to_id(u32 base)
> >>> +{
> >>> + int i;
> >>> +
> >>> + for (i = 0; i < ARRAY_SIZE(gce_subsys); i++)
> >>> + if (gce_subsys[i].base == base)
> >>> + return gce_subsys[i].id;
> >>> + return -EFAULT;
> >>> +}
> >>> +
> >>> +static int cmdq_eng_get_thread(u64 flag)
> >>> +{
> >>> + if (flag & BIT_ULL(CMDQ_ENG_DISP_DSI0))
> >>> + return CMDQ_THR_DISP_MAIN_IDX;
> >>> + else if (flag & BIT_ULL(CMDQ_ENG_DISP_DPI0))
> >>> + return CMDQ_THR_DISP_SUB_IDX;
> >>> + else
> >>> + return CMDQ_THR_DISP_MISC_IDX;
> >>> +}
> >>> +
> >>> +static void cmdq_task_release(struct cmdq_task *task)
> >>> +{
> >>> + struct cmdq *cmdq = task->cmdq;
> >>> +
> >>> + dma_free_coherent(cmdq->dev, task->command_size, task->va_base,
> >>> + task->pa_base);
> >>> + kfree(task);
> >>> +}
> >>> +
> >>> +static struct cmdq_task *cmdq_task_acquire(struct cmdq_rec *rec,
> >>> + struct cmdq_task_cb cb)
> >>> +{
> >>> + struct cmdq *cmdq = rec->cmdq;
> >>> + struct device *dev = cmdq->dev;
> >>> + struct cmdq_task *task;
> >>> +
> >>> + task = kzalloc(sizeof(*task), GFP_KERNEL);
> >>> + INIT_LIST_HEAD(&task->list_entry);
> >>> + task->va_base = dma_alloc_coherent(dev, rec->command_size,
> >>> + &task->pa_base, GFP_KERNEL);
> >>> + if (!task->va_base) {
> >>> + dev_err(dev, "allocate command buffer failed\n");
> >>> + kfree(task);
> >>> + return NULL;
> >>> + }
> >>> +
> >>> + task->cmdq = cmdq;
> >>> + task->command_size = rec->command_size;
> >>> + task->engine_flag = rec->engine_flag;
> >>> + task->task_state = TASK_STATE_BUSY;
> >>> + task->cb = cb;
> >>> + memcpy(task->va_base, rec->buf, rec->command_size);
> >>> + task->num_cmd = task->command_size / CMDQ_INST_SIZE;
> >>> + return task;
> >>> +}
> >>> +
> >>> +static void cmdq_thread_writel(struct cmdq_thread *thread, u32 value,
> >>> + u32 offset)
> >>> +{
> >>> + writel(value, thread->base + offset);
> >>> +}
> >>> +
> >>> +static u32 cmdq_thread_readl(struct cmdq_thread *thread, u32 offset)
> >>> +{
> >>> + return readl(thread->base + offset);
> >>> +}
> >>
> >> We can get rid of cmdq_thread_readl/writel.
> >
> > Will do.
> >
> >>> +
> >>> +static int cmdq_thread_suspend(struct cmdq *cmdq, struct cmdq_thread *thread)
> >>> +{
> >>> + u32 status;
> >>> +
> >>> + cmdq_thread_writel(thread, CMDQ_THR_SUSPEND, CMDQ_THR_SUSPEND_TASK);
> >>> +
> >>> + /* If already disabled, treat as suspended successful. */
> >>> + if (!(cmdq_thread_readl(thread, CMDQ_THR_ENABLE_TASK) &
> >>> + CMDQ_THR_ENABLED))
> >>> + return 0;
> >>> +
> >>> + if (readl_poll_timeout_atomic(thread->base + CMDQ_THR_CURR_STATUS,
> >>> + status, status & CMDQ_THR_STATUS_SUSPENDED, 0, 10)) {
> >>> + dev_err(cmdq->dev, "suspend GCE thread 0x%x failed\n",
> >>> + (u32)(thread->base - cmdq->base));
> >>> + return -EFAULT;
> >>> + }
> >>> +
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void cmdq_thread_resume(struct cmdq_thread *thread)
> >>> +{
> >>> + cmdq_thread_writel(thread, CMDQ_THR_RESUME, CMDQ_THR_SUSPEND_TASK);
> >>> +}
> >>> +
> >>> +static int cmdq_thread_reset(struct cmdq *cmdq, struct cmdq_thread *thread)
> >>> +{
> >>> + u32 warm_reset;
> >>> +
> >>> + cmdq_thread_writel(thread, CMDQ_THR_DO_WARM_RESET, CMDQ_THR_WARM_RESET);
> >>> + if (readl_poll_timeout_atomic(thread->base + CMDQ_THR_WARM_RESET,
> >>> + warm_reset, !(warm_reset & CMDQ_THR_DO_WARM_RESET),
> >>> + 0, 10)) {
> >>> + dev_err(cmdq->dev, "reset GCE thread 0x%x failed\n",
> >>> + (u32)(thread->base - cmdq->base));
> >>> + return -EFAULT;
> >>> + }
> >>> + writel(CMDQ_THR_ACTIVE_SLOT_CYCLES, cmdq->base + CMDQ_THR_SLOT_CYCLES);
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static void cmdq_thread_disable(struct cmdq *cmdq, struct cmdq_thread *thread)
> >>> +{
> >>> + cmdq_thread_reset(cmdq, thread);
> >>> + cmdq_thread_writel(thread, CMDQ_THR_DISABLED, CMDQ_THR_ENABLE_TASK);
> >>> +}
> >>> +
> >>> +/* notify GCE to re-fetch commands by setting GCE thread PC */
> >>> +static void cmdq_thread_invalidate_fetched_data(struct cmdq_thread *thread)
> >>> +{
> >>> + cmdq_thread_writel(thread,
> >>> + cmdq_thread_readl(thread, CMDQ_THR_CURR_ADDR),
> >>> + CMDQ_THR_CURR_ADDR);
> >>> +}
> >>> +
> >>> +static void cmdq_task_insert_into_thread(struct cmdq_task *task)
> >>> +{
> >>> + struct cmdq_thread *thread = task->thread;
> >>> + struct cmdq_task *prev_task = list_last_entry(
> >>> + &thread->task_busy_list, typeof(*task), list_entry);
> >>> + u64 *prev_task_base = prev_task->va_base;
> >>> +
> >>> + /* let previous task jump to this task */
> >>> + prev_task_base[prev_task->num_cmd - 1] = (u64)CMDQ_JUMP_BY_PA << 32 |
> >>> + task->pa_base;
> >>> +
> >>> + cmdq_thread_invalidate_fetched_data(thread);
> >>> +}
> >>> +
> >>> +/* we assume tasks in the same display GCE thread are waiting the same event. */
> >>> +static void cmdq_task_remove_wfe(struct cmdq_task *task)
> >>> +{
> >>> + u32 wfe_option = CMDQ_WFE_UPDATE | CMDQ_WFE_WAIT | CMDQ_WFE_WAIT_VALUE;
> >>> + u32 wfe_op = CMDQ_CODE_WFE << CMDQ_OP_CODE_SHIFT;
> >>> + u32 *base = task->va_base;
> >>> + u32 num_cmd = task->num_cmd << 1;
> >>> + int i;
> >>> +
> >>> + for (i = 0; i < num_cmd; i += 2)
> >>> + if (base[i] == wfe_option &&
> >>> + (base[i + 1] & CMDQ_OP_CODE_MASK) == wfe_op) {
> >>> + base[i] = CMDQ_JUMP_PASS;
> >>> + base[i + 1] = CMDQ_JUMP_BY_OFFSET;
> >>> + }
> >>
> >> After using the command buffer as a void pointer a u64 pointer, we now
> >> reference to it as u32. I would prefer to explain here, how the command
> >> looks like we are searching for and use a for loop passing task->num_cmd
> >> instead.
> >
> > Will use u64* to rewrite the above code.
> >
> >>> +}
> >>> +
> >>> +static void cmdq_task_exec(struct cmdq_task *task, struct cmdq_thread *thread)
> >>> +{
> >>> + struct cmdq *cmdq = task->cmdq;
> >>> + unsigned long flags;
> >>> + unsigned long curr_pa, end_pa;
> >>> +
> >>> + WARN_ON(clk_prepare_enable(cmdq->clock) < 0);
> >>> + spin_lock_irqsave(&cmdq->exec_lock, flags);
> >>
> >> cmdq_task_exec is called with cmdq->task_mutex held, so why do we need
> >> the spin_lock here? Can't we just use one of the two?
> >
> > We can drop task_mutex, but we will get some side effects.
> > 1. exec_lock needs to include more code, but I think it is not good for
> > spinlock.
> > 2. In cmdq_rec_flush_async(), task_mutex needs to protect
> > (1) cmdq->suspended, (2) cmdq_task_exec(), and
> > (3) cmdq_task_wait_release_schedule().
> > If we drop task_mutex, we have to put cmdq->suspended if condition
> > just before cmdq_task_exec() and inside exec_lock, and we have to
> > release task and its command buffer if error. This will let flow
> > become more complex and enlarge code size.
> >
> > What do you think?
>
> Why do you need to protect cmdq_task_wait_release_schedule? We don't
> care about the order of the workqueue elements, do we?

According to CK's comment, we have to ensure order to remove previous
task.
http://lists.infradead.org/pipermail/linux-mediatek/2016-May/005547.html

> As far as I understand you would need to protect cmdq_task_acquire as
> well, to "ensure" continously growing pa_base. More on that below.

We need to ensure continuous physical addresses in a task, but we don't
need to ensure continuous physical addresses between tasks.
So, I think it is unnecessary to protect by mutex or spinlock.

> >
> >>> + task->thread = thread;
> >>> + task->task_state = TASK_STATE_BUSY;
> >>
> >> That was already set in cmdq_task_acquire, why do we need to set it here
> >> again?
> >
> > Will drop it.
> >
>
> Yeah, but I think it makes more sense to drop it in cmdq_task_acquire
> instead.

Will drop it in cmdq_task_acquire instead.

> >>> + if (list_empty(&thread->task_busy_list)) {
> >>> + WARN_ON(cmdq_thread_reset(cmdq, thread) < 0);
> >>> +
> >>> + cmdq_thread_writel(thread, task->pa_base, CMDQ_THR_CURR_ADDR);
> >>> + cmdq_thread_writel(thread, task->pa_base + task->command_size,
> >>> + CMDQ_THR_END_ADDR);
> >>> + cmdq_thread_writel(thread, CMDQ_THR_PRIORITY, CMDQ_THR_CFG);
> >>> + cmdq_thread_writel(thread, CMDQ_THR_IRQ_EN,
> >>> + CMDQ_THR_IRQ_ENABLE);
> >>> +
> >>> + cmdq_thread_writel(thread, CMDQ_THR_ENABLED,
> >>> + CMDQ_THR_ENABLE_TASK);
> >>> + } else {
> >>> + WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> >>> +
> >>> + /*
> >>> + * check boundary condition
> >>> + * PC = END - 8, EOC is executed
> >>> + * PC = END, all CMDs are executed
> >>> + */
> >>> + curr_pa = cmdq_thread_readl(thread, CMDQ_THR_CURR_ADDR);
> >>> + end_pa = cmdq_thread_readl(thread, CMDQ_THR_END_ADDR);
> >>> + if (curr_pa == end_pa - 8 || curr_pa == end_pa) {
> >>
> >> 8 refers to CMDQ_INST_SIZE, right?
> >
> > Yes, I will use CMDQ_INST_SIZE.
> >
> >>> + /* set to this task directly */
> >>> + cmdq_thread_writel(thread, task->pa_base,
> >>> + CMDQ_THR_CURR_ADDR);
> >>> + } else {
> >>> + cmdq_task_insert_into_thread(task);
> >>> +
> >>> + if (thread == &cmdq->thread[CMDQ_THR_DISP_MAIN_IDX] ||
> >>> + thread == &cmdq->thread[CMDQ_THR_DISP_SUB_IDX])
> >>> + cmdq_task_remove_wfe(task);
> >>
> >> We could do this check using the task->engine_flag, I suppose that's
> >> easier to undestand then.
> >
> > Will use task->engine_flag.
> >
> >>> +
> >>> + smp_mb(); /* modify jump before enable thread */
> >>> + }
> >>> +
> >>> + cmdq_thread_writel(thread, task->pa_base + task->command_size,
> >>> + CMDQ_THR_END_ADDR);
> >>> + cmdq_thread_resume(thread);
> >>> + }
> >>> + list_move_tail(&task->list_entry, &thread->task_busy_list);
> >>> + spin_unlock_irqrestore(&cmdq->exec_lock, flags);
> >>> +}
> >>> +
> >>> +static void cmdq_handle_error_done(struct cmdq *cmdq,
> >>> + struct cmdq_thread *thread, u32 irq_flag)
> >>> +{
> >>> + struct cmdq_task *task, *tmp, *curr_task = NULL;
> >>> + u32 curr_pa;
> >>> + struct cmdq_cb_data cmdq_cb_data;
> >>> + bool err;
> >>> +
> >>> + if (irq_flag & CMDQ_THR_IRQ_ERROR)
> >>> + err = true;
> >>> + else if (irq_flag & CMDQ_THR_IRQ_DONE)
> >>> + err = false;
> >>> + else
> >>> + return;
> >>> +
> >>> + curr_pa = cmdq_thread_readl(thread, CMDQ_THR_CURR_ADDR);
> >>> +
> >>> + list_for_each_entry_safe(task, tmp, &thread->task_busy_list,
> >>> + list_entry) {
> >>> + if (curr_pa >= task->pa_base &&
> >>> + curr_pa < (task->pa_base + task->command_size))
> >>
> >> What are you checking here? It seems as if you make some implcit
> >> assumptions about pa_base and the order of execution of commands in the
> >> thread. Is it save to do so? Does dma_alloc_coherent give any guarantees
> >> about dma_handle?
> >
> > 1. Check what is the current running task in this GCE thread.
> > 2. Yes.
> > 3. Yes, CMDQ doesn't use iommu, so physical address is continuous.
> >
>
> Yes, physical addresses might be continous, but AFAIK there is no
> guarantee that the dma_handle address is steadily growing, when calling
> dma_alloc_coherent. And if I understand the code correctly, you use this
> assumption to decide if the task picked from task_busy_list is currently
> executing. So I think this mecanism is not working.

I don't use dma_handle address, and just use physical addresses.
>From CPU's point of view, tasks are linked by the busy list.
>From GCE's point of view, tasks are linked by the JUMP command.

> In which cases does the HW thread raise an interrupt.
> In case of error. When does CMDQ_THR_IRQ_DONE get raised?

GCE will raise interrupt if any task is done or error.
However, GCE is fast, so CPU may get multiple done tasks
when it is running ISR.

In case of error, that GCE thread will pause and raise interrupt.
So, CPU may get multiple done tasks and one error task.

> >>> + curr_task = task;
> >>> + if (task->cb.cb) {
> >>> + cmdq_cb_data.err = curr_task ? err : false;
> >>> + cmdq_cb_data.data = task->cb.data;
> >>> + task->cb.cb(cmdq_cb_data);
> >>> + }
> >>> + task->task_state = (curr_task && err) ? TASK_STATE_ERROR :
> >>> + TASK_STATE_DONE;
> >>> + list_del(&task->list_entry);
> >>> + if (curr_task)
> >>> + break;
> >>> + }
> >>> +
> >>> + wake_up(&thread->wait_task_done);
> >>> +}
> >>> +
> >>> +static void cmdq_thread_irq_handler(struct cmdq *cmdq, int tid)
> >>> +{
> >>> + struct cmdq_thread *thread = &cmdq->thread[tid];
> >>> + unsigned long flags = 0L;
> >>> + u32 irq_flag;
> >>> +
> >>> + spin_lock_irqsave(&cmdq->exec_lock, flags);
> >>> +
> >>> + irq_flag = cmdq_thread_readl(thread, CMDQ_THR_IRQ_STATUS);
> >>> + cmdq_thread_writel(thread, ~irq_flag, CMDQ_THR_IRQ_STATUS);
> >>> +
> >>> + /*
> >>> + * Another CPU core could run "release task" right before we acquire
> >>> + * the spin lock, and thus reset / disable this GCE thread, so we
> >>> + * need to check the enable bit of this GCE thread.
> >>> + */
> >>> + if (!(cmdq_thread_readl(thread, CMDQ_THR_ENABLE_TASK) &
> >>> + CMDQ_THR_ENABLED))
> >>> + irq_flag = 0;
> >>
> >> cmdq_handle_error_done just retuns in this case. Programming this way
> >> just makes things confusing. What about:
> >>
> >> if (cmdq_thread_readl(thread, CMDQ_THR_ENABLE_TASK) &
> >> CMDQ_THR_ENABLED)
> >> cmdq_handle_error_done(cmdq, thread, irq_flag);
> >> else
> >> irq_flag = 0;
> >>
> >> spin_unlock_irqrestore(&cmdq->exec_lock, flags);
> >
> > We still need to clear irq_flag if GCE thread is disabled.
> > So, I think we can just return here.
> >
> > if (!(cmdq_thread_readl(thread, CMDQ_THR_ENABLE_TASK) &
> > CMDQ_THR_ENABLED))
> > return;
> >
> > What do you think?
> >
>
> No, you can't just return, you need to unlock the spinlock.
> Anyway I would prefer it the other way round, as I put it in my last
> mail. Just delete the else branch, we don't need to set irq_flag to zero.

Sorry for my previous wrong reply since I merge your comment
and CK's comment.
http://lists.infradead.org/pipermail/linux-mediatek/2016-May/005547.html
So, I will put this if condition into cmdq_task_handle_error_result()
and then just return it if GCE thread is disabled.

> >>> +
> >>> + cmdq_handle_error_done(cmdq, thread, irq_flag);
> >>> + spin_unlock_irqrestore(&cmdq->exec_lock, flags);
> >>> +}
> >>> +
> >>> +static irqreturn_t cmdq_irq_handler(int irq, void *dev)
> >>> +{
> >>> + struct cmdq *cmdq = dev;
> >>> + u32 irq_status;
> >>> + int i;
> >>> +
> >>> + irq_status = readl(cmdq->base + CMDQ_CURR_IRQ_STATUS);
> >>> + irq_status &= CMDQ_IRQ_MASK;
> >>> + irq_status ^= CMDQ_IRQ_MASK;
> >>
> >> irq_status can be much bigger then 3, which is the number of threads in
> >> the system (CMDQ_THR_MAX_COUNT). So why we use this mask here isn't
> >> clear to me.
> >
> > Our GCE hardware has 16 threads, but we only use 3 threads currently.
> >
>
> Ok, but please use bitops here.

Will use bitops.

> >>> +
> >>> + if (!irq_status)
> >>> + return IRQ_NONE;
> >>> +
> >>> + while (irq_status) {
> >>> + i = ffs(irq_status) - 1;
> >>> + irq_status &= ~BIT(i);
> >>> + cmdq_thread_irq_handler(cmdq, i);
> >>> + }
> >>
> >> Can you explain how the irq status register looks like, that would it
> >> make much easier to understand what happens here.
> >
> > Bit 0 ~ 15 of irq status register represents GCE thread 0 ~ 15
> > interrupt. 0 means asserting interrupt; 1 means no interrupt.
> >
>
> Thanks, that helped. :)
>
> >>> +
> >>> + return IRQ_HANDLED;
> >>> +}
> >>> +
> >>> +static int cmdq_task_handle_error_result(struct cmdq_task *task)
> >>
> >> We never check the return values, why do we have them?
> >
> > Will drop return value.
> >
> >>> +{
> >>> + struct cmdq *cmdq = task->cmdq;
> >>> + struct device *dev = cmdq->dev;
> >>> + struct cmdq_thread *thread = task->thread;
> >>> + struct cmdq_task *next_task, *prev_task;
> >>> + u32 irq_flag;
> >>> +
> >>> + /* suspend GCE thread to ensure consistency */
> >>> + WARN_ON(cmdq_thread_suspend(cmdq, thread) < 0);
> >>> +
> >>> + /* ISR has handled this error task */
> >>> + if (task->task_state == TASK_STATE_ERROR) {
> >>> + next_task = list_first_entry_or_null(&thread->task_busy_list,
> >>> + struct cmdq_task, list_entry);
> >>> + if (next_task) /* move to next task */
> >>> + cmdq_thread_writel(thread, next_task->pa_base,
> >>> + CMDQ_THR_CURR_ADDR);
> >>
> >> We have to do this, as we suppose that the thread did not reach the jump
> >> instruction we put into it's command queue, right?
> >
> > Yes.
> >
>
> So this should then go into it's own function. In wait_release_work,
> something like this:
>
> if(task->task_state == TASK_STATE_ERROR)
> cmdq_task_handle_error(task)

OK.
I will write new function cmdq_task_handle_error() to handle error case.

> >>> + cmdq_thread_resume(thread);
> >>> + return -ECANCELED;
> >>> + }
> >>> +
> >>
> >> if task_state != ERROR and != DONE. This means that the timeout of
> >> task_release_wq has timed out, right?
> >
> > Yes.
> >
> >>> + /*
> >>> + * Save next_task and prev_task in advance
> >>> + * since cmdq_handle_error_done will remove list_entry.
> >>> + */
> >>> + next_task = prev_task = NULL;
> >>> + if (task->list_entry.next != &thread->task_busy_list)
> >>> + next_task = list_next_entry(task, list_entry);
> >>> + if (task->list_entry.prev != &thread->task_busy_list)
> >>> + prev_task = list_prev_entry(task, list_entry);
> >>> +
> >>> + /*
> >>> + * Although IRQ is disabled, GCE continues to execute.
> >>> + * It may have pending IRQ before GCE thread is suspended,
> >>> + * so check this condition again.
> >>> + */
> >>
> >> The first thing we did in this function was suspending the thread. Why
> >> do we need this then?
> >
> > Because timeout is CPU timeout not GCE timeout, GCE could just finish
> > this task before the GCE thread is suspended.
> >
>
> What are the reasons for a timeout? An error has happend, or the task is
> still executing.

>From GCE's point of view, this task is still executing.
But, it could be an error of client.
For example, task may never get event if display turn off hardware
before waiting for task to finish its work.

> >> To be honest this whole functions looks really like a design error. We
> >> have to sperate the states much clearer so that it is possible to
> >> understand what is happening in the GCE. Isn't it for example posible to
> >> have worker queues for timed out tasks and tasks with an error? I'm not
> >> sure how to do this, actually I'm not sure if I really understood how
> >> this is supposed to work.
> >
> > GCE doesn't have timeout. The timeout is decided and controlled by CPU,
> > so we check timeout in release work.
> > For error and done, they are easy to check by register, and we have
> > already created release work for timeout. So, I don't think we need to
> > create work queue for each case.
> >
> > What do you think?
> >
>
> I think, if we find in here, that the irq_flag is set, then the the
> interrupt handler was triggered and is spinning the spinlock. If this is
> not the case, we have a timeout and we handle this.

I will write another function to handle error, and handle timeout here.

> >> How much do we win, when we patch the thread command queue for every
> >> task we add, instead of just taking one task after another from the
> >> task_busy_list?
> >
> > GCE is used to help read/write registers with critical time limitation.
> > Sometimes, client may ask to process multiple tasks in a short period
> > of time, e.g. display flush multiple tasks for next vblank. So, CMDQ
> > shouldn't limit to process one task after another from the
> > task_busy_list. Currently, when interrupt or timeout, we will check
> > how many tasks are done, and which one is error or timeout.
> >
>
> So I suppose the device driver who use this are interested in throughput
> and not in latency. The callback of every
>
> >>> + irq_flag = cmdq_thread_readl(thread, CMDQ_THR_IRQ_STATUS);
> >>> + cmdq_handle_error_done(cmdq, thread, irq_flag);
> >>> + cmdq_thread_writel(thread, ~irq_flag, CMDQ_THR_IRQ_STATUS);
> >>> +
> >>> + if (task->task_state == TASK_STATE_DONE) {
> >>> + cmdq_thread_resume(thread);
> >>> + return 0;
> >>> + }
> >>> +
> >>> + if (task->task_state == TASK_STATE_ERROR) {
> >>> + dev_err(dev, "task 0x%p error\n", task);
> >>> + if (next_task) /* move to next task */
> >>> + cmdq_thread_writel(thread, next_task->pa_base,
> >>> + CMDQ_THR_CURR_ADDR);
> >>> + cmdq_thread_resume(thread);
> >>> + return -ECANCELED;
> >>> + }
> >>> +
> >>> + /* Task is running, so we force to remove it. */
> >>> + dev_err(dev, "task 0x%p timeout or killed\n", task);
> >>> + task->task_state = TASK_STATE_ERROR;
> >>> +
> >>> + if (prev_task) {
> >>> + u64 *prev_va = prev_task->va_base;
> >>> + u64 *curr_va = task->va_base;
> >>> +
> >>> + /* copy JUMP instruction */
> >>> + prev_va[prev_task->num_cmd - 1] = curr_va[task->num_cmd - 1];
> >>> +
> >>> + cmdq_thread_invalidate_fetched_data(thread);
> >>> + } else if (next_task) { /* move to next task */
> >>> + cmdq_thread_writel(thread, next_task->pa_base,
> >>> + CMDQ_THR_CURR_ADDR);
> >>> + }
> >>> +
> >>> + list_del(&task->list_entry);
> >>> + cmdq_thread_resume(thread);
> >>> +
> >>> + /* call cb here to prevent lock */
> >>> + if (task->cb.cb) {
> >>> + struct cmdq_cb_data cmdq_cb_data;
> >>> +
> >>> + cmdq_cb_data.err = true;
> >>> + cmdq_cb_data.data = task->cb.data;
> >>> + task->cb.cb(cmdq_cb_data);
> >>> + }
> >>> +
> >>> + return -ECANCELED;
> >>> +}
> >>> +
> >>> +static void cmdq_task_wait_release_work(struct work_struct *work_item)
> >>> +{
> >>> + struct cmdq_task *task = container_of(work_item, struct cmdq_task,
> >>> + release_work);
> >>> + struct cmdq *cmdq = task->cmdq;
> >>> + struct cmdq_thread *thread = task->thread;
> >>> + unsigned long flags;
> >>> +
> >>> + wait_event_timeout(thread->wait_task_done,
> >>> + task->task_state != TASK_STATE_BUSY,
> >>> + msecs_to_jiffies(CMDQ_TIMEOUT_MS));
> >>> +
> >>> + spin_lock_irqsave(&cmdq->exec_lock, flags);
> >>> + if (task->task_state != TASK_STATE_DONE)
> >>> + cmdq_task_handle_error_result(task);
> >>> + if (list_empty(&thread->task_busy_list))
> >>> + cmdq_thread_disable(cmdq, thread);
> >>> + spin_unlock_irqrestore(&cmdq->exec_lock, flags);
> >>> +
> >>> + /* release regardless of success or not */
> >>> + clk_disable_unprepare(cmdq->clock);
> >>> + cmdq_task_release(task);
> >>> +}
> >>> +
> >>> +static void cmdq_task_wait_release_schedule(struct cmdq_task *task)
> >>> +{
> >>> + struct cmdq *cmdq = task->cmdq;
> >>> +
> >>> + INIT_WORK(&task->release_work, cmdq_task_wait_release_work);
> >>> + queue_work(cmdq->task_release_wq, &task->release_work);
> >>> +}
> >>> +
> >>> +static int cmdq_rec_realloc_cmd_buffer(struct cmdq_rec *rec, size_t size)
> >>> +{
> >>> + void *new_buf;
> >>> +
> >>> + new_buf = krealloc(rec->buf, size, GFP_KERNEL | __GFP_ZERO);
> >>> + if (!new_buf)
> >>> + return -ENOMEM;
> >>> + rec->buf = new_buf;
> >>> + rec->buf_size = size;
> >>> + return 0;
> >>> +}
> >>> +
> >>> +struct cmdq_base *cmdq_register_device(struct device *dev)
> >>> +{
> >>> + struct cmdq_base *cmdq_base;
> >>> + struct resource res;
> >>> + int subsys;
> >>> + u32 base;
> >>> +
> >>> + if (of_address_to_resource(dev->of_node, 0, &res))
> >>> + return NULL;
> >>> + base = (u32)res.start;
> >>> +
> >>> + subsys = cmdq_subsys_base_to_id(base >> 16);
> >>> + if (subsys < 0)
> >>> + return NULL;
> >>> +
> >>> + cmdq_base = devm_kmalloc(dev, sizeof(*cmdq_base), GFP_KERNEL);
> >>> + if (!cmdq_base)
> >>> + return NULL;
> >>> + cmdq_base->subsys = subsys;
> >>> + cmdq_base->base = base;
> >>> +
> >>> + return cmdq_base;
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_register_device);
> >>> +
> >>> +int cmdq_rec_create(struct device *dev, u64 engine_flag,
> >>> + struct cmdq_rec **rec_ptr)
> >>> +{
> >>> + struct cmdq_rec *rec;
> >>> + int err;
> >>> +
> >>> + rec = kzalloc(sizeof(*rec), GFP_KERNEL);
> >>> + if (!rec)
> >>> + return -ENOMEM;
> >>> + rec->cmdq = dev_get_drvdata(dev);
> >>> + rec->engine_flag = engine_flag;
> >>> + err = cmdq_rec_realloc_cmd_buffer(rec, CMDQ_INITIAL_CMD_BLOCK_SIZE);
> >>
> >> Just pass PAGE_SIZE here, no need for CMDQ_INITIAL_CMD_BLOCK_SIZE.
> >
> > Will do.
> >
> >>> + if (err < 0) {
> >>> + kfree(rec);
> >>> + return err;
> >>> + }
> >>> + *rec_ptr = rec;
> >>> + return 0;
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_create);
> >>> +
> >>> +static int cmdq_rec_append_command(struct cmdq_rec *rec, enum cmdq_code code,
> >>> + u32 arg_a, u32 arg_b)
> >>> +{
> >>> + u64 *cmd_ptr;
> >>> + int err;
> >>> +
> >>> + if (WARN_ON(rec->finalized))
> >>> + return -EBUSY;
> >>> + if (code < CMDQ_CODE_MOVE || code > CMDQ_CODE_EOC)
> >>> + return -EINVAL;
> >>
> >> cmdq_rec_append_command is just called from inside this driver and code
> >> is a enum. We can expect it to be correct, no need for this check.
> >
> > Will drop this check.
> >
> >>> + if (unlikely(rec->command_size + CMDQ_INST_SIZE > rec->buf_size)) {
> >>
> >> command_size is the offset into the buffer to which a new command is
> >> written, so this name is highly confusing. I wonder if this would be
> >> easier to understand if we redefine command_size to something like the
> >> number of commands and divide/multiply CMDQ_INST_SIZE where this is needed.
> >
> > I can rename command_size to cmd_buf_size and calculate num_cmd by
> > dividing CMDQ_INST_SIZE.
> > What do you think?
> >
> >>> + err = cmdq_rec_realloc_cmd_buffer(rec, rec->buf_size * 2);
> >>> + if (err < 0)
> >>> + return err;
> >>> + }
> >>> + cmd_ptr = rec->buf + rec->command_size;
> >>> + (*cmd_ptr) = (u64)((code << CMDQ_OP_CODE_SHIFT) | arg_a) << 32 | arg_b;
> >>> + rec->command_size += CMDQ_INST_SIZE;
> >>> + return 0;
> >>> +}
> >>> +
> >>> +int cmdq_rec_write(struct cmdq_rec *rec, u32 value, struct cmdq_base *base,
> >>> + u32 offset)
> >>> +{
> >>> + u32 arg_a = ((base->base + offset) & CMDQ_ARG_A_WRITE_MASK) |
> >>> + ((base->subsys & CMDQ_SUBSYS_MASK) << CMDQ_SUBSYS_SHIFT);
> >>
> >> base->subsys is the id from gce_sybsys, so we can expect it to be
> >> correct, no need to mask with CMDQ_SUBSYS_MASK.
> >
> > Will drop it.
> >
> >>> + return cmdq_rec_append_command(rec, CMDQ_CODE_WRITE, arg_a, value);
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_write);
> >>> +
> >>> +int cmdq_rec_write_mask(struct cmdq_rec *rec, u32 value,
> >>> + struct cmdq_base *base, u32 offset, u32 mask)
> >>> +{
> >>> + u32 offset_mask = offset;
> >>> + int err;
> >>> +
> >>> + if (mask != 0xffffffff) {
> >>> + err = cmdq_rec_append_command(rec, CMDQ_CODE_MOVE, 0, ~mask);
> >>> + if (err < 0)
> >>> + return err;
> >>> + offset_mask |= CMDQ_WRITE_ENABLE_MASK;
> >>> + }
> >>> + return cmdq_rec_write(rec, value, base, offset_mask);
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_write_mask);
> >>> +
> >>> +int cmdq_rec_wfe(struct cmdq_rec *rec, enum cmdq_event event)
> >>> +{
> >>> + u32 arg_b;
> >>> +
> >>> + if (event >= CMDQ_MAX_HW_EVENT_COUNT || event < 0)
> >>> + return -EINVAL;
> >>> +
> >>> + /*
> >>> + * bit 0-11: wait value
> >>> + * bit 15: 1 - wait, 0 - no wait
> >>> + * bit 16-27: update value
> >>> + * bit 31: 1 - update, 0 - no update
> >>> + */
> >>
> >> I don't understand this comments. What are they for?
> >
> > This is for WFE command. I will comment it.
> >
> >>> + arg_b = CMDQ_WFE_UPDATE | CMDQ_WFE_WAIT | CMDQ_WFE_WAIT_VALUE;
> >>> + return cmdq_rec_append_command(rec, CMDQ_CODE_WFE, event, arg_b);
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_wfe);
> >>> +
> >>> +int cmdq_rec_clear_event(struct cmdq_rec *rec, enum cmdq_event event)
> >>> +{
> >>> + if (event >= CMDQ_MAX_HW_EVENT_COUNT || event < 0)
> >>> + return -EINVAL;
> >>> +
> >>> + return cmdq_rec_append_command(rec, CMDQ_CODE_WFE, event,
> >>> + CMDQ_WFE_UPDATE);
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_clear_event);
> >>> +
> >>> +static int cmdq_rec_finalize(struct cmdq_rec *rec)
> >>> +{
> >>> + int err;
> >>> +
> >>> + if (rec->finalized)
> >>> + return 0;
> >>> +
> >>> + /* insert EOC and generate IRQ for each command iteration */
> >>> + err = cmdq_rec_append_command(rec, CMDQ_CODE_EOC, 0, CMDQ_EOC_IRQ_EN);
> >>> + if (err < 0)
> >>> + return err;
> >>> +
> >>> + /* JUMP to end */
> >>> + err = cmdq_rec_append_command(rec, CMDQ_CODE_JUMP, 0, CMDQ_JUMP_PASS);
> >>> + if (err < 0)
> >>> + return err;
> >>> +
> >>
> >> Does this need to be atomic?
> >> What happens if after CODE_EOC and before CODE_JUMP some
> >> write/read/event gets added?
> >> What happens if more commands get added to the queue after CODE_JUMP,
> >> but before finalized is set to true. Why don't you use atomic functions
> >> to access finalized?
> >
> > Since cmdq_rec doesn't guarantee thread safe, mutex is needed when
> > client uses cmdq_rec.
> >
>
> Well I think that rec->finalized tries to implement this, but might
> fail, if two kernel threads work on the same cmdq_rec.
>
> >>> + rec->finalized = true;
> >>> + return 0;
> >>> +}
> >>> +
> >>> +int cmdq_rec_flush_async(struct cmdq_rec *rec, cmdq_async_flush_cb cb,
> >>> + void *data)
> >>> +{
> >>> + struct cmdq *cmdq = rec->cmdq;
> >>> + struct cmdq_task *task;
> >>> + struct cmdq_task_cb task_cb;
> >>> + struct cmdq_thread *thread;
> >>> + int err;
> >>> +
> >>> + mutex_lock(&cmdq->task_mutex);
> >>> + if (cmdq->suspended) {
> >>> + dev_err(cmdq->dev, "%s is called after suspended\n", __func__);
> >>> + mutex_unlock(&cmdq->task_mutex);
> >>> + return -EPERM;
> >>> + }
> >>> +
> >>> + err = cmdq_rec_finalize(rec);
> >>> + if (err < 0) {
> >>> + mutex_unlock(&cmdq->task_mutex);
> >>> + return err;
> >>> + }
> >>> +
> >>> + task_cb.cb = cb;
> >>> + task_cb.data = data;
> >>> + task = cmdq_task_acquire(rec, task_cb);
> >>> + if (!task) {
> >>> + mutex_unlock(&cmdq->task_mutex);
> >>> + return -EFAULT;
> >>> + }
> >>> +
> >>> + thread = &cmdq->thread[cmdq_eng_get_thread(task->engine_flag)];
> >>> + cmdq_task_exec(task, thread);
> >>> + cmdq_task_wait_release_schedule(task);
> >>> + mutex_unlock(&cmdq->task_mutex);
> >>> + return 0;
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_flush_async);
> >>> +
> >>> +struct cmdq_flush_completion {
> >>> + struct completion cmplt;
> >>> + bool err;
> >>> +};
> >>> +
> >>> +static int cmdq_rec_flush_cb(struct cmdq_cb_data data)
> >>> +{
> >>> + struct cmdq_flush_completion *cmplt = data.data;
> >>> +
> >>> + cmplt->err = data.err;
> >>> + complete(&cmplt->cmplt);
> >>> + return 0;
> >>> +}
> >>> +
> >>> +int cmdq_rec_flush(struct cmdq_rec *rec)
> >>> +{
> >>> + struct cmdq_flush_completion cmplt;
> >>> + int err;
> >>> +
> >>> + init_completion(&cmplt.cmplt);
> >>> + err = cmdq_rec_flush_async(rec, cmdq_rec_flush_cb, &cmplt);
> >>> + if (err < 0)
> >>> + return err;
> >>> + wait_for_completion(&cmplt.cmplt);
> >>> + return cmplt.err ? -EFAULT : 0;
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_flush);
> >>> +
> >>> +void cmdq_rec_destroy(struct cmdq_rec *rec)
> >>> +{
> >>> + kfree(rec->buf);
> >>> + kfree(rec);
> >>> +}
> >>> +EXPORT_SYMBOL(cmdq_rec_destroy);
> >>> +
> >>> +static bool cmdq_task_is_empty(struct cmdq *cmdq)
> >>> +{
> >>> + struct cmdq_thread *thread;
> >>> + int i;
> >>> +
> >>> + for (i = 0; i < ARRAY_SIZE(cmdq->thread); i++) {
> >>> + thread = &cmdq->thread[i];
> >>> + if (!list_empty(&thread->task_busy_list))
> >>> + return false;
> >>> + }
> >>> + return true;
> >>> +}
> >>> +
> >>> +static int cmdq_suspend(struct device *dev)
> >>> +{
> >>> + struct cmdq *cmdq = dev_get_drvdata(dev);
> >>> + u32 exec_threads;
> >>> +
> >>> + mutex_lock(&cmdq->task_mutex);
> >>> + cmdq->suspended = true;
> >>> + mutex_unlock(&cmdq->task_mutex);
> >>> +
> >>> + exec_threads = readl(cmdq->base + CMDQ_CURR_LOADED_THR);
> >>> + if ((exec_threads & CMDQ_THR_EXECUTING) && !cmdq_task_is_empty(cmdq)) {
> >>> + dev_err(dev, "wait active tasks timeout.\n");
> >>> + flush_workqueue(cmdq->task_release_wq);
> >>> + }
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int cmdq_resume(struct device *dev)
> >>> +{
> >>> + struct cmdq *cmdq = dev_get_drvdata(dev);
> >>> +
> >>> + cmdq->suspended = false;
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int cmdq_remove(struct platform_device *pdev)
> >>> +{
> >>> + struct cmdq *cmdq = platform_get_drvdata(pdev);
> >>> +
> >>> + destroy_workqueue(cmdq->task_release_wq);
> >>> + cmdq->task_release_wq = NULL;
> >>> + return 0;
> >>> +}
> >>> +
> >>> +static int cmdq_probe(struct platform_device *pdev)
> >>> +{
> >>> + struct device *dev = &pdev->dev;
> >>> + struct device_node *node = dev->of_node;
> >>> + struct resource *res;
> >>> + struct cmdq *cmdq;
> >>> + int err, i;
> >>> +
> >>> + cmdq = devm_kzalloc(dev, sizeof(*cmdq), GFP_KERNEL);
> >>> + if (!cmdq)
> >>> + return -ENOMEM;
> >>> + cmdq->dev = dev;
> >>> +
> >>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>> + cmdq->base = devm_ioremap_resource(dev, res);
> >>> + if (IS_ERR(cmdq->base)) {
> >>> + dev_err(dev, "failed to ioremap gce\n");
> >>> + return PTR_ERR(cmdq->base);
> >>> + }
> >>> +
> >>> + cmdq->irq = irq_of_parse_and_map(node, 0);
> >>> + if (!cmdq->irq) {
> >>> + dev_err(dev, "failed to get irq\n");
> >>> + return -EINVAL;
> >>> + }
> >>> +
> >>> + dev_dbg(dev, "cmdq device: addr:0x%p, va:0x%p, irq:%d\n",
> >>> + dev, cmdq->base, cmdq->irq);
> >>> +
> >>> + mutex_init(&cmdq->task_mutex);
> >>> + spin_lock_init(&cmdq->exec_lock);
> >>> + cmdq->task_release_wq = alloc_ordered_workqueue(
> >>> + "%s", WQ_MEM_RECLAIM | WQ_HIGHPRI,
> >>> + "cmdq_task_wait_release");
> >>> +
> >>> + for (i = 0; i < ARRAY_SIZE(cmdq->thread); i++) {
> >>> + cmdq->thread[i].base = cmdq->base + CMDQ_THR_BASE +
> >>> + CMDQ_THR_SHIFT * i;
> >>> + init_waitqueue_head(&cmdq->thread[i].wait_task_done);
> >>> + INIT_LIST_HEAD(&cmdq->thread[i].task_busy_list);
> >>> + }
> >>> +
> >>> + platform_set_drvdata(pdev, cmdq);
> >>> +
> >>> + err = devm_request_irq(dev, cmdq->irq, cmdq_irq_handler, IRQF_SHARED,
> >>> + CMDQ_DRIVER_DEVICE_NAME, cmdq);
> >>> + if (err < 0) {
> >>> + dev_err(dev, "failed to register ISR (%d)\n", err);
> >>> + goto fail;
> >>> + }
> >>> +
> >>> + cmdq->clock = devm_clk_get(dev, CMDQ_CLK_NAME);
> >>> + if (IS_ERR(cmdq->clock)) {
> >>> + dev_err(dev, "failed to get clk:%s\n", CMDQ_CLK_NAME);
> >>> + err = PTR_ERR(cmdq->clock);
> >>> + goto fail;
> >>> + }
> >>> + return 0;
> >>> +
> >>> +fail:
> >>> + cmdq_remove(pdev);
> >>> + return err;
> >>> +}
> >>> +
> >>> +static const struct dev_pm_ops cmdq_pm_ops = {
> >>> + .suspend = cmdq_suspend,
> >>> + .resume = cmdq_resume,
> >>> +};
> >>> +
> >>> +static const struct of_device_id cmdq_of_ids[] = {
> >>> + {.compatible = "mediatek,mt8173-gce",},
> >>> + {}
> >>> +};
> >>> +
> >>> +static struct platform_driver cmdq_drv = {
> >>> + .probe = cmdq_probe,
> >>> + .remove = cmdq_remove,
> >>> + .driver = {
> >>> + .name = CMDQ_DRIVER_DEVICE_NAME,
> >>> + .owner = THIS_MODULE,
> >>> + .pm = &cmdq_pm_ops,
> >>> + .of_match_table = cmdq_of_ids,
> >>> + }
> >>> +};
> >>> +
> >>> +builtin_platform_driver(cmdq_drv);
> >>> diff --git a/include/soc/mediatek/cmdq.h b/include/soc/mediatek/cmdq.h
> >>> new file mode 100644
> >>> index 0000000..60eef3d
> >>> --- /dev/null
> >>> +++ b/include/soc/mediatek/cmdq.h
> >>> @@ -0,0 +1,197 @@
> >>> +/*
> >>> + * Copyright (c) 2015 MediaTek Inc.
> >>> + *
> >>> + * This program is free software; you can redistribute it and/or modify
> >>> + * it under the terms of the GNU General Public License version 2 as
> >>> + * published by the Free Software Foundation.
> >>> + *
> >>> + * This program is distributed in the hope that it will be useful,
> >>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> >>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> >>> + * GNU General Public License for more details.
> >>> + */
> >>> +
> >>> +#ifndef __MTK_CMDQ_H__
> >>> +#define __MTK_CMDQ_H__
> >>> +
> >>> +#include <linux/platform_device.h>
> >>> +#include <linux/types.h>
> >>> +
> >>> +enum cmdq_eng {
> >>> + CMDQ_ENG_DISP_AAL,
> >>> + CMDQ_ENG_DISP_COLOR0,
> >>> + CMDQ_ENG_DISP_COLOR1,
> >>> + CMDQ_ENG_DISP_DPI0,
> >>> + CMDQ_ENG_DISP_DSI0,
> >>> + CMDQ_ENG_DISP_DSI1,
> >>> + CMDQ_ENG_DISP_GAMMA,
> >>> + CMDQ_ENG_DISP_OD,
> >>> + CMDQ_ENG_DISP_OVL0,
> >>> + CMDQ_ENG_DISP_OVL1,
> >>> + CMDQ_ENG_DISP_PWM0,
> >>> + CMDQ_ENG_DISP_PWM1,
> >>> + CMDQ_ENG_DISP_RDMA0,
> >>> + CMDQ_ENG_DISP_RDMA1,
> >>> + CMDQ_ENG_DISP_RDMA2,
> >>> + CMDQ_ENG_DISP_UFOE,
> >>> + CMDQ_ENG_DISP_WDMA0,
> >>> + CMDQ_ENG_DISP_WDMA1,
> >>> + CMDQ_ENG_MAX,
> >>> +};
> >>> +
> >>> +/* events for CMDQ and display */
> >>> +enum cmdq_event {
> >>> + /* Display start of frame(SOF) events */
> >>> + CMDQ_EVENT_DISP_OVL0_SOF = 11,
> >>> + CMDQ_EVENT_DISP_OVL1_SOF = 12,
> >>> + CMDQ_EVENT_DISP_RDMA0_SOF = 13,
> >>> + CMDQ_EVENT_DISP_RDMA1_SOF = 14,
> >>> + CMDQ_EVENT_DISP_RDMA2_SOF = 15,
> >>> + CMDQ_EVENT_DISP_WDMA0_SOF = 16,
> >>> + CMDQ_EVENT_DISP_WDMA1_SOF = 17,
> >>> + /* Display end of frame(EOF) events */
> >>> + CMDQ_EVENT_DISP_OVL0_EOF = 39,
> >>> + CMDQ_EVENT_DISP_OVL1_EOF = 40,
> >>> + CMDQ_EVENT_DISP_RDMA0_EOF = 41,
> >>> + CMDQ_EVENT_DISP_RDMA1_EOF = 42,
> >>> + CMDQ_EVENT_DISP_RDMA2_EOF = 43,
> >>> + CMDQ_EVENT_DISP_WDMA0_EOF = 44,
> >>> + CMDQ_EVENT_DISP_WDMA1_EOF = 45,
> >>> + /* Mutex end of frame(EOF) events */
> >>> + CMDQ_EVENT_MUTEX0_STREAM_EOF = 53,
> >>> + CMDQ_EVENT_MUTEX1_STREAM_EOF = 54,
> >>> + CMDQ_EVENT_MUTEX2_STREAM_EOF = 55,
> >>> + CMDQ_EVENT_MUTEX3_STREAM_EOF = 56,
> >>> + CMDQ_EVENT_MUTEX4_STREAM_EOF = 57,
> >>> + /* Display underrun events */
> >>> + CMDQ_EVENT_DISP_RDMA0_UNDERRUN = 63,
> >>> + CMDQ_EVENT_DISP_RDMA1_UNDERRUN = 64,
> >>> + CMDQ_EVENT_DISP_RDMA2_UNDERRUN = 65,
> >>> + /* Keep this at the end of HW events */
> >>> + CMDQ_MAX_HW_EVENT_COUNT = 260,
> >>> +};
> >>> +
> >>> +struct cmdq_cb_data {
> >>> + bool err;
> >>> + void *data;
> >>> +};
> >>> +
> >>> +typedef int (*cmdq_async_flush_cb)(struct cmdq_cb_data data);
> >>> +
> >>> +struct cmdq_task;
> >>> +struct cmdq;
> >>> +
> >>> +struct cmdq_rec {
> >>> + struct cmdq *cmdq;
> >>> + u64 engine_flag;
> >>> + size_t command_size;
> >>> + void *buf;
> >>> + size_t buf_size;
> >>> + bool finalized;
> >>> +};
>
> Why do we need cmdq_rec at all? Can't we just use the cmdq_task for that
> and this way make the driver less complex?

There are two main reasons for cmdq_rec.
1. It is slow to access dma too frequently.
So, we append commands to cacheable memory, and then flush to dma.
2. cmdq_rec is not thread safe, but cmdq_task needs thread safe.
If we merge them, we need to take care of some synchronization
issues.

> >>> +
> >>> +struct cmdq_base {
> >>> + int subsys;
> >>> + u32 base;
> >>
> >> subsys can always be calculated via cmdq_subsys_base_to_id(base >> 16)
> >> so we can get rid of the struct, right?
> >
> > Current subsys method is based on previous comment from Daniel Kurtz.
> > Please take a look of our previous discussion.
> > http://lists.infradead.org/pipermail/linux-mediatek/2016-February/004483.html
> > Thanks.
> >
>
> I have to look deeper into this, but from what I read, the proposal from
> Daniel [1] seems good to me.
>
> [1] https://patchwork.kernel.org/patch/8068311/

The initial proposal has some problem, so please see the follow-up
discussions. Thanks.
http://lists.infradead.org/pipermail/linux-mediatek/2016-February/003972.html
http://lists.infradead.org/pipermail/linux-mediatek/2016-February/004483.html

> >>> +};
> >>> +
> >>> +/**
> >>> + * cmdq_register_device() - register device which needs CMDQ
> >>> + * @dev: device
> >>> + *
> >>> + * Return: cmdq_base pointer or NULL for failed
> >>> + */
> >>> +struct cmdq_base *cmdq_register_device(struct device *dev);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_create() - create command queue record
> >>> + * @dev: device
> >>> + * @engine_flag: command queue engine flag
> >>> + * @rec_ptr: command queue record pointer to retrieve cmdq_rec
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + */
> >>> +int cmdq_rec_create(struct device *dev, u64 engine_flag,
> >>> + struct cmdq_rec **rec_ptr);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_write() - append write command to the command queue record
> >>> + * @rec: the command queue record
> >>> + * @value: the specified target register value
> >>> + * @base: the command queue base
> >>> + * @offset: register offset from module base
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + */
> >>> +int cmdq_rec_write(struct cmdq_rec *rec, u32 value,
> >>> + struct cmdq_base *base, u32 offset);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_write_mask() - append write command with mask to the command
> >>> + * queue record
> >>> + * @rec: the command queue record
> >>> + * @value: the specified target register value
> >>> + * @base: the command queue base
> >>> + * @offset: register offset from module base
> >>> + * @mask: the specified target register mask
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + */
> >>> +int cmdq_rec_write_mask(struct cmdq_rec *rec, u32 value,
> >>> + struct cmdq_base *base, u32 offset, u32 mask);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_wfe() - append wait for event command to the command queue reco rd
> >>
> >> reco rd -> record
> >
> > Will fix it.
> >
> >> Regards,
> >> Matthias
> >>
> >>> + * @rec: the command queue record
> >>> + * @event: the desired event type to "wait and CLEAR"
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + */
> >>> +int cmdq_rec_wfe(struct cmdq_rec *rec, enum cmdq_event event);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_clear_event() - append clear event command to the command queue
> >>> + * record
> >>> + * @rec: the command queue record
> >>> + * @event: the desired event to be cleared
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + */
> >>> +int cmdq_rec_clear_event(struct cmdq_rec *rec, enum cmdq_event event);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_flush() - trigger CMDQ to execute the recorded commands
> >>> + * @rec: the command queue record
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + *
> >>> + * Trigger CMDQ to execute the recorded commands. Note that this is a
> >>> + * synchronous flush function. When the function returned, the recorded
> >>> + * commands have been done.
> >>> + */
> >>> +int cmdq_rec_flush(struct cmdq_rec *rec);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_flush_async() - trigger CMDQ to asynchronously execute the recorded
> >>> + * commands and call back after ISR is finished
> >>> + * @rec: the command queue record
> >>> + * @cb: called in the end of CMDQ ISR
> >>> + * @data: this data will pass back to cb
> >>> + *
> >>> + * Return: 0 for success; else the error code is returned
> >>> + *
> >>> + * Trigger CMDQ to asynchronously execute the recorded commands and call back
> >>> + * after ISR is finished. Note that this is an ASYNC function. When the function
> >>> + * returned, it may or may not be finished. The ISR callback function is called
> >>> + * in the end of ISR.
>
> "The callback is called from the ISR."
>
> Regards,
> Matthias
>
> >>> + */
> >>> +int cmdq_rec_flush_async(struct cmdq_rec *rec, cmdq_async_flush_cb cb,
> >>> + void *data);
> >>> +
> >>> +/**
> >>> + * cmdq_rec_destroy() - destroy command queue record
> >>> + * @rec: the command queue record
> >>> + */
> >>> +void cmdq_rec_destroy(struct cmdq_rec *rec);
> >>> +
> >>> +#endif /* __MTK_CMDQ_H__ */
> >>>
> >
> > Thanks,
> > HS
> >

Thanks,
HS