[PATCH] drm/ast: Inline drm_simple_encoder_init()

[Thomas Zimmermann]

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.

Best regards
Thomas

>

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)