Hi,
Am Mittwoch, dem 14.06.2023 um 00:42 +0800 schrieb Sui Jingfeng:
> Hi, Lucas
>
>
> I love your patch, perhaps something to improve:
>
> The MLCG stand for "Module Level Clock Gating",
>
> without reading the commit message, I guess there may have people don't
> know its meaning.
>
Yea, I expect people to read the commit message and not just the
subject if they want to know what a patch does. The MLCG abbreviation
is already well established within the driver code.
> There are still more thing in this patch can only be understand relay on
> guessing... :-)
>
That's unfortunately true. I don't know exactly what the pulse eater
control bits mean either. I've taken them verbatim from the reset
sequence in the Vivante kernel driver, which is also why I didn't try
to assign some meaning by giving them a name, but keep them as BITs in
the driver code.
Regards,
Lucas
>
> But drm/etnaviv drvier still works with this patch applied, so
>
>
> On 2023/6/7 20:58, Lucas Stach wrote:
> > Module level clock gating and the pulse eater might interfere with
> > the GPU reset, as they both have the potential to stop the clock
> > and thus reset propagation to parts of the GPU.
> >
> > Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> > Reviewed-by: Christian Gmeiner <cgmeiner@xxxxxxxxxx>
>
>
> Tested-by: Sui Jingfeng <suijingfeng@xxxxxxxxxxx>
>
>
> > ---
> > I'm not aware of any cases where this would have been an issue, but
> > it is what the downstream driver does and fundametally seems like
> > the right thing to do.
> > ---
> > drivers/gpu/drm/etnaviv/etnaviv_gpu.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > index de8c9894967c..41aab1aa330b 100644
> > --- a/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > +++ b/drivers/gpu/drm/etnaviv/etnaviv_gpu.c
> > @@ -505,8 +505,19 @@ static int etnaviv_hw_reset(struct etnaviv_gpu *gpu)
> > timeout = jiffies + msecs_to_jiffies(1000);
> >
> > while (time_is_after_jiffies(timeout)) {
> > - /* enable clock */
> > unsigned int fscale = 1 << (6 - gpu->freq_scale);
> > + u32 pulse_eater = 0x01590880;
> > +
> > + /* disable clock gating */
> > + gpu_write_power(gpu, VIVS_PM_POWER_CONTROLS, 0x0);
> > +
> > + /* disable pulse eater */
> > + pulse_eater |= BIT(17);
> > + gpu_write_power(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
> > + pulse_eater |= BIT(0);
> > + gpu_write_power(gpu, VIVS_PM_PULSE_EATER, pulse_eater);
> > +
> > + /* enable clock */
> > control = VIVS_HI_CLOCK_CONTROL_FSCALE_VAL(fscale);
> > etnaviv_gpu_load_clock(gpu, control);
> >
>
