Re: [PATCH v7 07/15] drm/imx: dc: Add PRG support

[Liu Ying <victor.liu@nxp.com>]

On Thu, Oct 29, 2026 at 11:30:55AM +0200, Laurentiu Palcu wrote:
> On Mon, Oct 26, 2026 at 06:05:12PM +0800, Liu Ying wrote:

[...]

> > diff --git a/drivers/gpu/drm/imx/dc/dc-prg.c b/drivers/gpu/drm/imx/dc/dc-prg.c
> > new file mode 100644
> > index 000000000000..43df5683b24d
> > --- /dev/null
> > +++ b/drivers/gpu/drm/imx/dc/dc-prg.c
> > @@ -0,0 +1,314 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright 2025 NXP
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/bitops.h>
> 
> This header can be removed.

Done.

> 
> > +#include <linux/bits.h>
> > +#include <linux/cleanup.h>
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/device.h>
> > +#include <linux/list.h>
> > +#include <linux/module.h>
> 
> This one too.

Done.

> 
> [...]
> 
> > +
> > +void dc_prg_disable(struct dc_prg *prg)
> > +{
> > +	regmap_write(prg->reg, PRG_CTRL, BYPASS);
> > +
> > +	pm_runtime_put(prg->dev);
> 
> I have a question about this. I see Sashiko also flagged an issue regarding the
> unconditional put when the pm_runtime_resume_and_get() fails in
> dc_prg_configure(). The resume is, probably, unlikely to fail.

Yes, dc_prg_configure() is only called at atomic commit stage which is supposed
to run successfully without any error.  If pm_runtime_resume_and_get() fails
there, something should be fixed, so I don't bother to handle the failing case.

> But, I see a
> situation where the dc_prg_configure() is never called: when the plane is
> invisible. The dc_prg_disable() would still be called in flush() when the plane
> is disabled, would it not?

Yes, patch 15 doesn't handle the invisible plane properly with the prefetch
engine enabled.  I'll fix this in next version in patch 15.

[...]

> > +bool dc_prg_stride_supported(struct dc_prg *prg,
> 
> It looks like you're not using prg. Can it be removed?

dc_dprc_stride_supported() in patch 8 uses it, so it cannot be removed.

-- 
Regards,
Liu Ying