[PATCH] drm/ast: Inline drm_simple_encoder_init()

[Dmitry Baryshkov]

On Wed, 26 Jun 2024 at 12:19, Thomas Zimmermann <tzimmermann at suse.de> wrote:
>
> Hi
>
> Am 26.06.24 um 11:10 schrieb Dmitry Baryshkov:
> > On Wed, Jun 26, 2024 at 11:01:11AM GMT, Thomas Zimmermann wrote:
> >> Hi
> >>
> >> Am 26.06.24 um 06:34 schrieb Dmitry Baryshkov:
> >>> On Tue, Jun 25, 2024 at 03:18:09PM GMT, Thomas Zimmermann wrote:
> >>>> The function drm_simple_encoder_init() is a trivial helper and
> >>>> deprecated. Replace it with the regular call to drm_encoder_init().
> >>>> Resolves the dependency on drm_simple_kms_helper.h. No functional
> >>>> changes.
> >>>>
> >>>> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> >>>> ---
> >>>>    drivers/gpu/drm/ast/ast_mode.c | 45 ++++++++++++++++++++++++++++++----
> >>>>    1 file changed, 40 insertions(+), 5 deletions(-)
> >>>>
> >>>> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> >>>> index 6695af70768f..2fd9c78eab73 100644
> >>>> --- a/drivers/gpu/drm/ast/ast_mode.c
> >>>> +++ b/drivers/gpu/drm/ast/ast_mode.c
> >>>> @@ -45,7 +45,6 @@
> >>>>    #include <drm/drm_managed.h>
> >>>>    #include <drm/drm_panic.h>
> >>>>    #include <drm/drm_probe_helper.h>
> >>>> -#include <drm/drm_simple_kms_helper.h>
> >>>>    #include "ast_ddc.h"
> >>>>    #include "ast_drv.h"
> >>>> @@ -1358,6 +1357,14 @@ static int ast_crtc_init(struct drm_device *dev)
> >>>>            return 0;
> >>>>    }
> >>>> +/*
> >>>> + * VGA Encoder
> >>>> + */
> >>>> +
> >>>> +static const struct drm_encoder_funcs ast_vga_encoder_funcs = {
> >>>> +  .destroy = drm_encoder_cleanup,
> >>>> +};
> >>>> +
> >>>>    /*
> >>>>     * VGA Connector
> >>>>     */
> >>>> @@ -1411,7 +1418,8 @@ static int ast_vga_output_init(struct ast_device *ast)
> >>>>            struct drm_connector *connector = &ast->output.vga.connector;
> >>>>            int ret;
> >>>> -  ret = drm_simple_encoder_init(dev, encoder, DRM_MODE_ENCODER_DAC);
> >>>> +  ret = drm_encoder_init(dev, encoder, &ast_vga_encoder_funcs,
> >>>> +                         DRM_MODE_ENCODER_DAC, NULL);
> >>> What about using drmm_encoder_init() instead? It will call
> >>> drm_encoder_cleanup automatically.
> >> IIRC the original use case for the drmm_encoder_*() funcs was to solve
> >> problems with the clean-up order if the encoder was added dynamically. The
> >> hardware for ast is entirely static and ast uses drmm_mode_config_init() for
> >> auto-cleaning up the modesetting pipeline. Using drmm_encoder_init() seems
> >> like a bit of wasted resources for no gain.
> > I'd say it's qui pro quo. We are wasting resources on drmm handling, but
> > then keep it by dropping all drm_encoder_funcs instances.
>
> With drm_encoder_init() there's a static-const declared struct in RO
> memory. With drmm_encoder_init(), there's a kalloc for the managed
> callback data. It's RW memory and the alloc can fail. Therefore I prefer
> drm_encoder_init() in this case.

Ack.

-- 
With best wishes
Dmitry