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

Matthias Brugger
2016-05-31T20:04:16Z

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 ?

>>> + 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.

>>> + 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?

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.

>
>>> + 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.

>>> + 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.

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

>>> + 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.

>>> +
>>> + 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.

>>> +
>>> + 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)

>>> + 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.

>> 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.

>> 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?

>>> +
>>> +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/

>>> +};
>>> +
>>> +/**
>>> + * 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
>