Re: [PATCH v3 1/4] drm/rockchip: vop: export line flag function

Yakir Yang
2016-07-08T02:30:42Z

Sean,

On 07/01/2016 11:32 PM, Sean Paul wrote:
> On Fri, Jul 1, 2016 at 11:30 AM, Sean Paul <seanpaul@chromium.org> wrote:
>> On Fri, Jul 1, 2016 at 5:19 AM, Yakir Yang <ykk@rock-chips.com> wrote:
>>> VOP have integrated a hardware counter which indicate the exact display
>>> line that vop is scanning. And if we're interested in a specific line,
>>> we can set the line number to vop line_flag register, and then vop would
>>> generate a line_flag interrupt for it.
>>>
>>> For example eDP PSR function is interested in the vertical blanking
>>> period, then driver could set the line number to zero.
>>>
>>> This patch have exported a symbol that allow other driver to listen the
>>> line flag event with given timeout limit:
>>> - rockchip_drm_wait_line_flag()
>>>
>>> Signed-off-by: Yakir Yang <ykk@rock-chips.com>
>>> ---
>>> Changes in v3:
>>> - Export the 'rockchip_drm_wait_line_flag' symbol, and document it.
>>> - Add 'line_flag_num_0' for RK3288/RK3036
>>> - Remove the notify for waiting line_flag event (Daniel)
>>>
>>> Changes in v2:
>>> - Introduce in v2, split VOP line flag changes out
>>>
>>> drivers/gpu/drm/rockchip/rockchip_drm_drv.h | 3 +
>>> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 103 ++++++++++++++++++++++++++++
>>> drivers/gpu/drm/rockchip/rockchip_drm_vop.h | 3 +
>>> drivers/gpu/drm/rockchip/rockchip_vop_reg.c | 4 ++
>>> 4 files changed, 113 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
>>> index ea39329..239b830 100644
>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
>>> @@ -70,4 +70,7 @@ int rockchip_drm_dma_attach_device(struct drm_device *drm_dev,
>>> struct device *dev);
>>> void rockchip_drm_dma_detach_device(struct drm_device *drm_dev,
>>> struct device *dev);
>>> +int rockchip_drm_wait_line_flag(struct drm_crtc *crtc, unsigned int line_num,
>>> + unsigned int mstimeout);
>>> +
>>> #endif /* _ROCKCHIP_DRM_DRV_H_ */
>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>> index c8a62a8..cd3cac5 100644
>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>> @@ -121,6 +121,8 @@ struct vop {
>>> /* protected by dev->event_lock */
>>> struct drm_pending_vblank_event *event;
>>>
>>> + struct completion line_flag_completion;
>>> +
>>> const struct vop_data *data;
>>>
>>> uint32_t *regsbak;
>>> @@ -431,6 +433,59 @@ static void vop_dsp_hold_valid_irq_disable(struct vop *vop)
>>> spin_unlock_irqrestore(&vop->irq_lock, flags);
>>> }
>>>
>>> +/*
>>> + * (1) each frame starts at the start of the Vsync pulse which is signaled by
>>> + * the "FRAME_SYNC" interrupt.
>>> + * (2) the active data region of each frame ends at dsp_vact_end
>>> + * (3) we should program this same number (dsp_vact_end) into dsp_line_frag_num,
>>> + * to get "LINE_FLAG" interrupt at the end of the active on screen data.
>>> + *
>>> + * VOP_INTR_CTRL0.dsp_line_frag_num = VOP_DSP_VACT_ST_END.dsp_vact_end
>>> + * Interrupts
>>> + * LINE_FLAG -------------------------------+
>>> + * FRAME_SYNC ----+ |
>>> + * | |
>>> + * v v
>>> + * | Vsync | Vbp | Vactive | Vfp |
>>> + * ^ ^ ^ ^
>>> + * | | | |
>>> + * | | | |
>>> + * dsp_vs_end ------------+ | | | VOP_DSP_VTOTAL_VS_END
>>> + * dsp_vact_start --------------+ | | VOP_DSP_VACT_ST_END
>>> + * dsp_vact_end ----------------------------+ | VOP_DSP_VACT_ST_END
>>> + * dsp_total -------------------------------------+ VOP_DSP_VTOTAL_VS_END
>>> + */
>>> +
>>> +static void vop_line_flag_irq_enable(struct vop *vop, int line_num)
>>> +{
>>> + unsigned long flags;
>>> +
>>> + if (WARN_ON(!vop->is_enabled))
>>> + return;
>>> +
>>> + spin_lock_irqsave(&vop->irq_lock, flags);
>>> +
>>> + VOP_CTRL_SET(vop, line_flag_num_0, line_num);
>>> + VOP_INTR_SET_TYPE(vop, enable, LINE_FLAG_INTR, 1);
>>> + vop_cfg_done(vop);
>>> +
>>> + spin_unlock_irqrestore(&vop->irq_lock, flags);
>>> +}
>>> +
>>> +static void vop_line_flag_irq_disable(struct vop *vop)
>>> +{
>>> + unsigned long flags;
>>> +
>>> + if (WARN_ON(!vop->is_enabled))
>>> + return;
>>> +
>>> + spin_lock_irqsave(&vop->irq_lock, flags);
>>> +
>>> + VOP_INTR_SET_TYPE(vop, enable, LINE_FLAG_INTR, 0);
>>> +
>>> + spin_unlock_irqrestore(&vop->irq_lock, flags);
>>> +}
>>> +
>>> static void vop_enable(struct drm_crtc *crtc)
>>> {
>>> struct vop *vop = to_vop(crtc);
>>> @@ -1157,6 +1212,13 @@ static irqreturn_t vop_isr(int irq, void *data)
>>> ret = IRQ_HANDLED;
>>> }
>>>
>>> + if (active_irqs & LINE_FLAG_INTR) {
>>> + if (!completion_done(&vop->line_flag_completion))
>>> + complete(&vop->line_flag_completion);
>> I think there's potential to miss flags here if the timing is just
>> right because the completion_done and complete are not atomic wrt the
>> wait_line_flag function. I think you need some locking around the
>> completion operations to ensure they're properly sequenced.
>>
>> FWIW, if you're reinitializing the completion every time in
>> drm_wait_line_flag, you should be able to just call complete (or
>> complete_all) without checking if there are any waiters.
>>
> I should add, if you just call complete/complete_all() here, you
> shouldn't need to add locking (assuming only one waiter).

Yes, only one waiter.

>>> + active_irqs &= ~LINE_FLAG_INTR;
>>> + ret = IRQ_HANDLED;
>>> + }
>>> +
>>> if (active_irqs & FS_INTR) {
>>> drm_crtc_handle_vblank(crtc);
>>> vop_handle_vblank(vop);
>>> @@ -1255,6 +1317,7 @@ static int vop_create_crtc(struct vop *vop)
>>>
>>> init_completion(&vop->dsp_hold_completion);
>>> init_completion(&vop->wait_update_complete);
>>> + init_completion(&vop->line_flag_completion);
>>> crtc->port = port;
>>> rockchip_register_crtc_funcs(crtc, &private_crtc_funcs);
>>>
>>> @@ -1411,6 +1474,46 @@ static void vop_win_init(struct vop *vop)
>>> }
>>> }
>>>
>>> +/**
>>> + * rockchip_drm_wait_line_flag - acqiure the give line flag event
>>> + * @crtc: CRTC to enable line flag
>>> + * @line_num: interested line number
>>> + * @mstimeout: millisecond for timeout
>>> + *
>>> + * Driver would hold here until the interested line flag interrupt have
>>> + * happened or timeout to wait.
>>> + *
>>> + * Returns:
>>> + * Zero on success, negative errno on failure.
>>> + */
>>> +int rockchip_drm_wait_line_flag(struct drm_crtc *crtc, unsigned int line_num,
>>> + unsigned int mstimeout)
>>> +{
>>> + struct vop *vop = to_vop(crtc);
>>> + unsigned long jiffies_left;
>>> +
>>> + if (!crtc || !vop->is_enabled)
>>> + return -ENODEV;
>>> +
>>> + if (line_num > crtc->mode.vtotal || mstimeout <= 0)
>>> + return -EINVAL;
>>> +
>>> + reinit_completion(&vop->line_flag_completion);
>>> + vop_line_flag_irq_enable(vop, line_num);
>>> +
>> This will only work for one waiter per vop. Is it worth enforcing this
>> explicitly to avoid weird behavior when there are more than one?

Yes, you're right, need to avoid the weird behavior here.

>>
>>> + jiffies_left = wait_for_completion_timeout(&vop->line_flag_completion,
>>> + msecs_to_jiffies(mstimeout));
>>> + vop_line_flag_irq_disable(vop);
>>> +
>>> + if (jiffies_left == 0) {
>>> + dev_err(vop->dev, "Timeout waiting for IRQ\n");
>>> + return -ETIMEDOUT;
>>> + }
>>> +
>>> + return 0;
>>> +}
>>> +EXPORT_SYMBOL(rockchip_drm_wait_line_flag);
>>> +
>>> static int vop_bind(struct device *dev, struct device *master, void *data)
>>> {
>>> struct platform_device *pdev = to_platform_device(dev);
>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
>>> index ff4f52e..34fcd03 100644
>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
>>> @@ -61,6 +61,9 @@ struct vop_ctrl {
>>> struct vop_reg hpost_st_end;
>>> struct vop_reg vpost_st_end;
>>>
>>> + struct vop_reg line_flag_num_0;
>>> + struct vop_reg line_flag_num_1;
>>> +
>> nit: you could make this an array:
>>
>> struct vop_reg line_flag_num[2];

Done,

>>
>>> struct vop_reg cfg_done;
>>> };
>>>
>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
>>> index 6f42e56..e9211c9 100644
>>> --- a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
>>> +++ b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
>>> @@ -122,6 +122,7 @@ static const struct vop_ctrl rk3036_ctrl_data = {
>>> .hact_st_end = VOP_REG(RK3036_DSP_HACT_ST_END, 0x1fff1fff, 0),
>>> .vtotal_pw = VOP_REG(RK3036_DSP_VTOTAL_VS_END, 0x1fff1fff, 0),
>>> .vact_st_end = VOP_REG(RK3036_DSP_VACT_ST_END, 0x1fff1fff, 0),
>>> + .line_flag_num_0 = VOP_REG(RK3036_INT_STATUS, 0xfff, 12),
>>> .cfg_done = VOP_REG(RK3036_REG_CFG_DONE, 0x1, 0),
>>> };
>>>
>>> @@ -221,6 +222,7 @@ static const struct vop_ctrl rk3288_ctrl_data = {
>>> .vact_st_end = VOP_REG(RK3288_DSP_VACT_ST_END, 0x1fff1fff, 0),
>>> .hpost_st_end = VOP_REG(RK3288_POST_DSP_HACT_INFO, 0x1fff1fff, 0),
>>> .vpost_st_end = VOP_REG(RK3288_POST_DSP_VACT_INFO, 0x1fff1fff, 0),
>>> + .line_flag_num_0 = VOP_REG(RK3288_INTR_CTRL0, 0x1fff, 12),
>>> .cfg_done = VOP_REG(RK3288_REG_CFG_DONE, 0x1, 0),
>>> };
>>>
>>> @@ -299,6 +301,8 @@ static const struct vop_ctrl rk3399_ctrl_data = {
>>> .vact_st_end = VOP_REG(RK3399_DSP_VACT_ST_END, 0x1fff1fff, 0),
>>> .hpost_st_end = VOP_REG(RK3399_POST_DSP_HACT_INFO, 0x1fff1fff, 0),
>>> .vpost_st_end = VOP_REG(RK3399_POST_DSP_VACT_INFO, 0x1fff1fff, 0),
>>> + .line_flag_num_0 = VOP_REG(RK3399_LINE_FLAG, 0xffff, 0),
>>> + .line_flag_num_1 = VOP_REG(RK3399_LINE_FLAG, 0xffff, 16),
>>> .cfg_done = VOP_REG_MASK(RK3399_REG_CFG_DONE, 0x1, 0),
>>> };
>>>
>>> --
>>> 1.9.1
>>>
>>>
>
>