Re: [PATCH] drm/rockchip: vop: do axi reset in vop initial time

[Yakir Yang]

On 06/01/2016 11:19 PM, Thierry Reding wrote:
> On Wed, Jun 01, 2016 at 05:19:12PM +0800, Yakir Yang wrote:
> > There is a bug in RK3399 VOP, when bootloader/kernel only enable
> > VOP Big or VOP Little to display, then VOP IOMMU would failed to
> > reset at the initial time and VOP register couldn't write rightly.
> >
> > After do the pure reset of VOP module, then things back to right.
> >
> > Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 15 ++++++++++++++-
> >   1 file changed, 14 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> > index 1c4d5b5..4150323 100644
> > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
> > @@ -1292,7 +1292,7 @@ static int vop_initial(struct vop *vop)
> >   {
> >   	const struct vop_data *vop_data = vop->data;
> >   	const struct vop_reg_data *init_table = vop_data->init_table;
> > -	struct reset_control *ahb_rst;
> > +	struct reset_control *ahb_rst, *axi_rst;
> >   	int i, ret;
> >   
> >   	vop->hclk = devm_clk_get(vop->dev, "hclk_vop");
> > @@ -1331,6 +1331,19 @@ static int vop_initial(struct vop *vop)
> >   	}
> >   
> >   	/*
> > +	 * do aclk_reset, reset all vop registers.
> > +	 */
> > +	axi_rst = devm_reset_control_get(vop->dev, "axi");
> I don't think you want the managed version here since you only store
> this in a local variable and hence aren't going to need it afterwards.
> Just use reset_control_get() and ...

Great, but seems Mark would not accept this fix now :(
Maybe I should found the root cause why my bootloader/kernel would 
broken the VOP.

Thanks,
- Yakir
> > +	if (IS_ERR(axi_rst)) {
> > +		dev_err(vop->dev, "failed to get axi reset\n");
> > +		ret = PTR_ERR(axi_rst);
> > +		goto err_disable_aclk;
> > +	}
> > +	reset_control_assert(axi_rst);
> > +	usleep_range(10, 20);
> > +	reset_control_deassert(axi_rst);
> call reset_control_put() here.
>
> > +
> > +	/*
> >   	 * do hclk_reset, reset all vop registers.
> >   	 */
> >   	ahb_rst = devm_reset_control_get(vop->dev, "ahb");
> This uses the same pattern, so you might want to consider reworking this
> as well, though it should be a separate patch.
>
> Thierry