Hi Mark, Heiko,
On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao <[email protected]> wrote:
> Vop standby will take effect end of current frame,
> if dsp_hold_valid_irq happen, it means vop standby complete.
>
> we must wait standby complete when we want to disable aclk,
> if not, memory bus maybe dead.
>
> Signed-off-by: Mark Yao <[email protected]>
> ---
> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 76 ++++++++++++++++++++++-----
> 1 file changed, 63 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> index fb25836..47ea61f 100644
> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> @@ -89,6 +89,7 @@ struct vop {
> /* mutex vsync_ work */
> struct mutex vsync_mutex;
> bool vsync_work_pending;
> + struct completion dsp_hold_completion;
>
> const struct vop_data *data;
>
> @@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format)
> }
> }
>
> +static void vop_dsp_hold_valid_irq_enable(struct vop *vop)
> +{
> + unsigned long flags;
> +
> + BUG_ON(!vop->is_enabled);
Re: Heiko "use a WARN_ON":
If the VOP clock is off, then the system will just hang when trying to
write the VOP register so in this case, BUG_ON gives a more reliable
crash dump than the hang.
> +
> + spin_lock_irqsave(&vop->irq_lock, flags);
> +
> + vop_mask_write(vop, INTR_CTRL0, DSP_HOLD_VALID_INTR_MASK,
> + DSP_HOLD_VALID_INTR_EN(1));
> +
> + spin_unlock_irqrestore(&vop->irq_lock, flags);
> +}
> +
> +static void vop_dsp_hold_valid_irq_disable(struct vop *vop)
> +{
> + unsigned long flags;
> +
> + BUG_ON(!vop->is_enabled);
> +
> + spin_lock_irqsave(&vop->irq_lock, flags);
> +
> + vop_mask_write(vop, INTR_CTRL0, DSP_HOLD_VALID_INTR_MASK,
> + DSP_HOLD_VALID_INTR_EN(0));
> +
> + spin_unlock_irqrestore(&vop->irq_lock, flags);
> +}
> +
> static void vop_enable(struct drm_crtc *crtc)
> {
> struct vop *vop = to_vop(crtc);
> @@ -454,26 +483,36 @@ static void vop_disable(struct drm_crtc *crtc)
>
> drm_vblank_off(crtc->dev, vop->pipe);
>
> - disable_irq(vop->irq);
> -
> /*
> - * TODO: Since standby doesn't take effect until the next vblank,
> - * when we turn off dclk below, the vop is probably still active.
> + * Vop standby will take effect until end of current frame,
"Vop standby will take effect at end of current frame"
> + * if dsp hold valid irq happen, it means standby complete.
> + *
> + * we must wait standby complete when we want to disable aclk,
> + * if not, memory bus maybe dead.
> */
> + reinit_completion(&vop->dsp_hold_completion);
> + vop_dsp_hold_valid_irq_enable(vop);
> +
> spin_lock(&vop->reg_lock);
>
> VOP_CTRL_SET(vop, standby, 1);
>
> spin_unlock(&vop->reg_lock);
>
> + wait_for_completion(&vop->dsp_hold_completion);
> +
> + vop_dsp_hold_valid_irq_disable(vop);
> +
> + disable_irq(vop->irq);
> +
> vop->is_enabled = false;
> +
> /*
> - * disable dclk to stop frame scan, so we can safely detach iommu,
> + * vop standby complete, so iommu detach is safe.
> */
> - clk_disable(vop->dclk);
> -
> rockchip_drm_dma_detach_device(vop->drm_dev, vop->dev);
>
> + clk_disable(vop->dclk);
> clk_disable(vop->aclk);
> clk_disable(vop->hclk);
> }
> @@ -1086,6 +1125,7 @@ static irqreturn_t vop_isr(int irq, void *data)
> struct vop *vop = data;
> uint32_t intr0_reg, active_irqs;
> unsigned long flags;
> + int ret = IRQ_NONE;
>
> /*
> * INTR_CTRL0 register has interrupt status, enable and clear bits, we
> @@ -1104,15 +1144,24 @@ static irqreturn_t vop_isr(int irq, void *data)
> if (!active_irqs)
> return IRQ_NONE;
>
> - /* Only Frame Start Interrupt is enabled; other irqs are spurious. */
> - if (!(active_irqs & FS_INTR)) {
> - DRM_ERROR("Unknown VOP IRQs: %#02x\n", active_irqs);
> - return IRQ_NONE;
> + if (active_irqs & DSP_HOLD_VALID_INTR) {
> + if (!completion_done(&vop->dsp_hold_completion))
Why is this "completion_done" check needed?
I guess it doesn't help, but isn't strictly needed, since the
dsp_hold_completion is a one shot, right?
In any case, this should work as it is, so:
Reviewed-by: Daniel Kurtz <[email protected]>
> + complete(&vop->dsp_hold_completion);
> + active_irqs &= ~DSP_HOLD_VALID_INTR;
> + ret = IRQ_HANDLED;
> }
>
> - drm_handle_vblank(vop->drm_dev, vop->pipe);
> + if (active_irqs & FS_INTR) {
> + drm_handle_vblank(vop->drm_dev, vop->pipe);
> + active_irqs &= ~FS_INTR;
> + ret = (vop->vsync_work_pending) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
> + }
>
> - return (vop->vsync_work_pending) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
> + /* Unhandled irqs are spurious. */
> + if (active_irqs)
> + DRM_ERROR("Unknown VOP IRQs: %#02x\n", active_irqs);
> +
> + return ret;
> }
>
> static int vop_create_crtc(struct vop *vop)
> @@ -1194,6 +1243,7 @@ static int vop_create_crtc(struct vop *vop)
> goto err_cleanup_crtc;
> }
>
> + init_completion(&vop->dsp_hold_completion);
> crtc->port = port;
> vop->pipe = drm_crtc_index(crtc);
> rockchip_register_crtc_funcs(drm_dev, &private_crtc_funcs, vop->pipe);
> --
> 1.7.9.5
>
>
On 2015年02月02日 10:07, Daniel Kurtz wrote:
> Hi Mark, Heiko,
>
> On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao <[email protected]> wrote:
>> Vop standby will take effect end of current frame,
>> if dsp_hold_valid_irq happen, it means vop standby complete.
>>
>> we must wait standby complete when we want to disable aclk,
>> if not, memory bus maybe dead.
>>
>> Signed-off-by: Mark Yao <[email protected]>
>> ---
>> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 76 ++++++++++++++++++++++-----
>> 1 file changed, 63 insertions(+), 13 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>> index fb25836..47ea61f 100644
>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>> @@ -89,6 +89,7 @@ struct vop {
>> /* mutex vsync_ work */
>> struct mutex vsync_mutex;
>> bool vsync_work_pending;
>> + struct completion dsp_hold_completion;
>>
>> const struct vop_data *data;
>>
>> @@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format)
>> }
>> }
>>
>> +static void vop_dsp_hold_valid_irq_enable(struct vop *vop)
>> +{
>> + unsigned long flags;
>> +
>> + BUG_ON(!vop->is_enabled);
> Re: Heiko "use a WARN_ON":
>
> If the VOP clock is off, then the system will just hang when trying to
> write the VOP register so in this case, BUG_ON gives a more reliable
> crash dump than the hang.
In this way, you are right, if vop clocks is disabled, write vop
register will hang system, and the WARN_ON
crash dump may be have no chance to print.
>
>> +
>> + spin_lock_irqsave(&vop->irq_lock, flags);
>> +
>> + vop_mask_write(vop, INTR_CTRL0, DSP_HOLD_VALID_INTR_MASK,
>> + DSP_HOLD_VALID_INTR_EN(1));
>> +
>> + spin_unlock_irqrestore(&vop->irq_lock, flags);
>> +}
>> +
>> +static void vop_dsp_hold_valid_irq_disable(struct vop *vop)
>> +{
>> + unsigned long flags;
>> +
>> + BUG_ON(!vop->is_enabled);
>> +
>> + spin_lock_irqsave(&vop->irq_lock, flags);
>> +
>> + vop_mask_write(vop, INTR_CTRL0, DSP_HOLD_VALID_INTR_MASK,
>> + DSP_HOLD_VALID_INTR_EN(0));
>> +
>> + spin_unlock_irqrestore(&vop->irq_lock, flags);
>> +}
>> +
>> static void vop_enable(struct drm_crtc *crtc)
>> {
>> struct vop *vop = to_vop(crtc);
>> @@ -454,26 +483,36 @@ static void vop_disable(struct drm_crtc *crtc)
>>
>> drm_vblank_off(crtc->dev, vop->pipe);
>>
>> - disable_irq(vop->irq);
>> -
>> /*
>> - * TODO: Since standby doesn't take effect until the next vblank,
>> - * when we turn off dclk below, the vop is probably still active.
>> + * Vop standby will take effect until end of current frame,
> "Vop standby will take effect at end of current frame"
OK
>> + * if dsp hold valid irq happen, it means standby complete.
>> + *
>> + * we must wait standby complete when we want to disable aclk,
>> + * if not, memory bus maybe dead.
>> */
>> + reinit_completion(&vop->dsp_hold_completion);
>> + vop_dsp_hold_valid_irq_enable(vop);
>> +
>> spin_lock(&vop->reg_lock);
>>
>> VOP_CTRL_SET(vop, standby, 1);
>>
>> spin_unlock(&vop->reg_lock);
>>
>> + wait_for_completion(&vop->dsp_hold_completion);
>> +
>> + vop_dsp_hold_valid_irq_disable(vop);
>> +
>> + disable_irq(vop->irq);
>> +
>> vop->is_enabled = false;
>> +
>> /*
>> - * disable dclk to stop frame scan, so we can safely detach iommu,
>> + * vop standby complete, so iommu detach is safe.
>> */
>> - clk_disable(vop->dclk);
>> -
>> rockchip_drm_dma_detach_device(vop->drm_dev, vop->dev);
>>
>> + clk_disable(vop->dclk);
>> clk_disable(vop->aclk);
>> clk_disable(vop->hclk);
>> }
>> @@ -1086,6 +1125,7 @@ static irqreturn_t vop_isr(int irq, void *data)
>> struct vop *vop = data;
>> uint32_t intr0_reg, active_irqs;
>> unsigned long flags;
>> + int ret = IRQ_NONE;
>>
>> /*
>> * INTR_CTRL0 register has interrupt status, enable and clear bits, we
>> @@ -1104,15 +1144,24 @@ static irqreturn_t vop_isr(int irq, void *data)
>> if (!active_irqs)
>> return IRQ_NONE;
>>
>> - /* Only Frame Start Interrupt is enabled; other irqs are spurious. */
>> - if (!(active_irqs & FS_INTR)) {
>> - DRM_ERROR("Unknown VOP IRQs: %#02x\n", active_irqs);
>> - return IRQ_NONE;
>> + if (active_irqs & DSP_HOLD_VALID_INTR) {
>> + if (!completion_done(&vop->dsp_hold_completion))
> Why is this "completion_done" check needed?
> I guess it doesn't help, but isn't strictly needed, since the
> dsp_hold_completion is a one shot, right?
Right, the DSP_HOLD_VALID_INTR only happen when standby complete, one
standby one irq.
Mark
> In any case, this should work as it is, so:
>
> Reviewed-by: Daniel Kurtz <[email protected]>
>
>> + complete(&vop->dsp_hold_completion);
>> + active_irqs &= ~DSP_HOLD_VALID_INTR;
>> + ret = IRQ_HANDLED;
>> }
>>
>> - drm_handle_vblank(vop->drm_dev, vop->pipe);
>> + if (active_irqs & FS_INTR) {
>> + drm_handle_vblank(vop->drm_dev, vop->pipe);
>> + active_irqs &= ~FS_INTR;
>> + ret = (vop->vsync_work_pending) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
>> + }
>>
>> - return (vop->vsync_work_pending) ? IRQ_WAKE_THREAD : IRQ_HANDLED;
>> + /* Unhandled irqs are spurious. */
>> + if (active_irqs)
>> + DRM_ERROR("Unknown VOP IRQs: %#02x\n", active_irqs);
>> +
>> + return ret;
>> }
>>
>> static int vop_create_crtc(struct vop *vop)
>> @@ -1194,6 +1243,7 @@ static int vop_create_crtc(struct vop *vop)
>> goto err_cleanup_crtc;
>> }
>>
>> + init_completion(&vop->dsp_hold_completion);
>> crtc->port = port;
>> vop->pipe = drm_crtc_index(crtc);
>> rockchip_register_crtc_funcs(drm_dev, &private_crtc_funcs, vop->pipe);
>> --
>> 1.7.9.5
>>
>>
>
>
On Mon, Feb 02, 2015 at 10:30:09AM +0800, Mark yao wrote:
> On 2015年02月02日 10:07, Daniel Kurtz wrote:
> >Hi Mark, Heiko,
> >
> >On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao <[email protected]> wrote:
> >>Vop standby will take effect end of current frame,
> >>if dsp_hold_valid_irq happen, it means vop standby complete.
> >>
> >>we must wait standby complete when we want to disable aclk,
> >>if not, memory bus maybe dead.
> >>
> >>Signed-off-by: Mark Yao <[email protected]>
> >>---
> >> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 76 ++++++++++++++++++++++-----
> >> 1 file changed, 63 insertions(+), 13 deletions(-)
> >>
> >>diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> >>index fb25836..47ea61f 100644
> >>--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> >>+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> >>@@ -89,6 +89,7 @@ struct vop {
> >> /* mutex vsync_ work */
> >> struct mutex vsync_mutex;
> >> bool vsync_work_pending;
> >>+ struct completion dsp_hold_completion;
> >>
> >> const struct vop_data *data;
> >>
> >>@@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format)
> >> }
> >> }
> >>
> >>+static void vop_dsp_hold_valid_irq_enable(struct vop *vop)
> >>+{
> >>+ unsigned long flags;
> >>+
> >>+ BUG_ON(!vop->is_enabled);
> >Re: Heiko "use a WARN_ON":
> >
> >If the VOP clock is off, then the system will just hang when trying to
> >write the VOP register so in this case, BUG_ON gives a more reliable
> >crash dump than the hang.
> In this way, you are right, if vop clocks is disabled, write vop register
> will hang system, and the WARN_ON
if (WARN_ON(cond))
return;
is what we commonly use in i915. Because it's really not any good to use
BUG_ON in drm drivers, at least if you expect anyone to use fbcon on top
of it (i.e. anything even remotely resembling a normal distro): Then the
intial modeset is all done under console_lock, which means that _none_ of
your BUG_ON will ever get out over serial console.
The problem is fbcon locking, but no fool yet signed up to fix it (it's
horrible, I looked ...).
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
On 2015年02月02日 15:53, Daniel Vetter wrote:
> On Mon, Feb 02, 2015 at 10:30:09AM +0800, Mark yao wrote:
>> On 2015年02月02日 10:07, Daniel Kurtz wrote:
>>> Hi Mark, Heiko,
>>>
>>> On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao <[email protected]> wrote:
>>>> Vop standby will take effect end of current frame,
>>>> if dsp_hold_valid_irq happen, it means vop standby complete.
>>>>
>>>> we must wait standby complete when we want to disable aclk,
>>>> if not, memory bus maybe dead.
>>>>
>>>> Signed-off-by: Mark Yao <[email protected]>
>>>> ---
>>>> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 76 ++++++++++++++++++++++-----
>>>> 1 file changed, 63 insertions(+), 13 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>> index fb25836..47ea61f 100644
>>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>> @@ -89,6 +89,7 @@ struct vop {
>>>> /* mutex vsync_ work */
>>>> struct mutex vsync_mutex;
>>>> bool vsync_work_pending;
>>>> + struct completion dsp_hold_completion;
>>>>
>>>> const struct vop_data *data;
>>>>
>>>> @@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format)
>>>> }
>>>> }
>>>>
>>>> +static void vop_dsp_hold_valid_irq_enable(struct vop *vop)
>>>> +{
>>>> + unsigned long flags;
>>>> +
>>>> + BUG_ON(!vop->is_enabled);
>>> Re: Heiko "use a WARN_ON":
>>>
>>> If the VOP clock is off, then the system will just hang when trying to
>>> write the VOP register so in this case, BUG_ON gives a more reliable
>>> crash dump than the hang.
>> In this way, you are right, if vop clocks is disabled, write vop register
>> will hang system, and the WARN_ON
> if (WARN_ON(cond))
> return;
>
> is what we commonly use in i915. Because it's really not any good to use
> BUG_ON in drm drivers, at least if you expect anyone to use fbcon on top
> of it (i.e. anything even remotely resembling a normal distro): Then the
> intial modeset is all done under console_lock, which means that _none_ of
> your BUG_ON will ever get out over serial console.
>
> The problem is fbcon locking, but no fool yet signed up to fix it (it's
> horrible, I looked ...).
> -Daniel
I know this problem, if fbcon locking, and BUG_ON, we can't get any log
from serial console, Trouble
me many times. So know, if no drm log output, the first thing I do is
remove the fbcon lock, and then
we can see the crash dump.
But here, I expect to use BUG_ON, because if BUG happen, vop register
will hang system, and WARN_ON
may be have no chance to output.
Mark
On Feb 4, 2015 11:38 AM, "Mark yao" <[email protected]> wrote:
>
> On 2015年02月02日 15:53, Daniel Vetter wrote:
>>
>> On Mon, Feb 02, 2015 at 10:30:09AM +0800, Mark yao wrote:
>>>
>>> On 2015年02月02日 10:07, Daniel Kurtz wrote:
>>>>
>>>> Hi Mark, Heiko,
>>>>
>>>> On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao <[email protected]> wrote:
>>>>>
>>>>> Vop standby will take effect end of current frame,
>>>>> if dsp_hold_valid_irq happen, it means vop standby complete.
>>>>>
>>>>> we must wait standby complete when we want to disable aclk,
>>>>> if not, memory bus maybe dead.
>>>>>
>>>>> Signed-off-by: Mark Yao <[email protected]>
>>>>> ---
>>>>> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 76 ++++++++++++++++++++++-----
>>>>> 1 file changed, 63 insertions(+), 13 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>>> index fb25836..47ea61f 100644
>>>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>>> @@ -89,6 +89,7 @@ struct vop {
>>>>> /* mutex vsync_ work */
>>>>> struct mutex vsync_mutex;
>>>>> bool vsync_work_pending;
>>>>> + struct completion dsp_hold_completion;
>>>>>
>>>>> const struct vop_data *data;
>>>>>
>>>>> @@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format)
>>>>> }
>>>>> }
>>>>>
>>>>> +static void vop_dsp_hold_valid_irq_enable(struct vop *vop)
>>>>> +{
>>>>> + unsigned long flags;
>>>>> +
>>>>> + BUG_ON(!vop->is_enabled);
>>>>
>>>> Re: Heiko "use a WARN_ON":
>>>>
>>>> If the VOP clock is off, then the system will just hang when trying to
>>>> write the VOP register so in this case, BUG_ON gives a more reliable
>>>> crash dump than the hang.
>>>
>>> In this way, you are right, if vop clocks is disabled, write vop register
>>> will hang system, and the WARN_ON
>>
>> if (WARN_ON(cond))
>> return;
>>
>> is what we commonly use in i915. Because it's really not any good to use
>> BUG_ON in drm drivers, at least if you expect anyone to use fbcon on top
>> of it (i.e. anything even remotely resembling a normal distro): Then the
>> intial modeset is all done under console_lock, which means that _none_ of
>> your BUG_ON will ever get out over serial console.
>>
>> The problem is fbcon locking, but no fool yet signed up to fix it (it's
>> horrible, I looked ...).
>> -Daniel
>
> I know this problem, if fbcon locking, and BUG_ON, we can't get any log from serial console, Trouble
> me many times. So know, if no drm log output, the first thing I do is remove the fbcon lock, and then
> we can see the crash dump.
>
> But here, I expect to use BUG_ON, because if BUG happen, vop register will hang system, and WARN_ON
> may be have no chance to output.
Yeah, but danvet is suggesting we just return immediately on the
WARN_ON condition, to avoid accessing the vop registers and hanging.
Thus, the WARN_ON will have a chance to put out (unless the early
return path goes off and finds some other unprotected path goes to
access unlocked registers).
-Dan
>
> Mark
>
On 2015年02月04日 11:48, Daniel Kurtz wrote:
> On Feb 4, 2015 11:38 AM, "Mark yao" <[email protected]> wrote:
>> On 2015年02月02日 15:53, Daniel Vetter wrote:
>>> On Mon, Feb 02, 2015 at 10:30:09AM +0800, Mark yao wrote:
>>>> On 2015年02月02日 10:07, Daniel Kurtz wrote:
>>>>> Hi Mark, Heiko,
>>>>>
>>>>> On Sat, Jan 31, 2015 at 4:41 PM, Mark Yao <[email protected]> wrote:
>>>>>> Vop standby will take effect end of current frame,
>>>>>> if dsp_hold_valid_irq happen, it means vop standby complete.
>>>>>>
>>>>>> we must wait standby complete when we want to disable aclk,
>>>>>> if not, memory bus maybe dead.
>>>>>>
>>>>>> Signed-off-by: Mark Yao <[email protected]>
>>>>>> ---
>>>>>> drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 76 ++++++++++++++++++++++-----
>>>>>> 1 file changed, 63 insertions(+), 13 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>>>> index fb25836..47ea61f 100644
>>>>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
>>>>>> @@ -89,6 +89,7 @@ struct vop {
>>>>>> /* mutex vsync_ work */
>>>>>> struct mutex vsync_mutex;
>>>>>> bool vsync_work_pending;
>>>>>> + struct completion dsp_hold_completion;
>>>>>>
>>>>>> const struct vop_data *data;
>>>>>>
>>>>>> @@ -382,6 +383,34 @@ static bool is_alpha_support(uint32_t format)
>>>>>> }
>>>>>> }
>>>>>>
>>>>>> +static void vop_dsp_hold_valid_irq_enable(struct vop *vop)
>>>>>> +{
>>>>>> + unsigned long flags;
>>>>>> +
>>>>>> + BUG_ON(!vop->is_enabled);
>>>>> Re: Heiko "use a WARN_ON":
>>>>>
>>>>> If the VOP clock is off, then the system will just hang when trying to
>>>>> write the VOP register so in this case, BUG_ON gives a more reliable
>>>>> crash dump than the hang.
>>>> In this way, you are right, if vop clocks is disabled, write vop register
>>>> will hang system, and the WARN_ON
>>> if (WARN_ON(cond))
>>> return;
>>>
>>> is what we commonly use in i915. Because it's really not any good to use
>>> BUG_ON in drm drivers, at least if you expect anyone to use fbcon on top
>>> of it (i.e. anything even remotely resembling a normal distro): Then the
>>> intial modeset is all done under console_lock, which means that _none_ of
>>> your BUG_ON will ever get out over serial console.
>>>
>>> The problem is fbcon locking, but no fool yet signed up to fix it (it's
>>> horrible, I looked ...).
>>> -Daniel
>> I know this problem, if fbcon locking, and BUG_ON, we can't get any log from serial console, Trouble
>> me many times. So know, if no drm log output, the first thing I do is remove the fbcon lock, and then
>> we can see the crash dump.
>>
>> But here, I expect to use BUG_ON, because if BUG happen, vop register will hang system, and WARN_ON
>> may be have no chance to output.
> Yeah, but danvet is suggesting we just return immediately on the
> WARN_ON condition, to avoid accessing the vop registers and hanging.
>
> Thus, the WARN_ON will have a chance to put out (unless the early
> return path goes off and finds some other unprotected path goes to
> access unlocked registers).
>
> -Dan
All right, I got it.
>> Mark
>>
>
>
--
Ｍark Yao 姚智情
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