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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH 1/9] drm/arcpgu: replace struct drm_simple_display_pipe with regular atomic helpers
On Mon Jul 6, 2026 at 4:01 PM CST, Thomas Zimmermann wrote:
> Hi
>
> Am 04.07.26 um 20:31 schrieb Ze Huang:
>> Instantiate plane, CRTC and encoder directly and wire them up with
>> standard atomic helpers.
>>
>> This removes arcpgu's dependency on deprecated simple-KMS display pipe
>> interface.
>>
>> Signed-off-by: Ze Huang <ze.huang@xxxxxxxxxxxxxxxx>
>> ---
>> drivers/gpu/drm/tiny/arcpgu.c | 165
>> +++++++++++++++++++++++++++++++++---------
>> 1 file changed, 131 insertions(+), 34 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/tiny/arcpgu.c b/drivers/gpu/drm/tiny/arcpgu.c
>> index c93d61ac0bb7..375cdb79e4e8 100644
>> --- a/drivers/gpu/drm/tiny/arcpgu.c
>> +++ b/drivers/gpu/drm/tiny/arcpgu.c
>> @@ -17,12 +17,12 @@
>> #include <drm/drm_fbdev_dma.h>
>> #include <drm/drm_fourcc.h>
>> #include <drm/drm_framebuffer.h>
>> +#include <drm/drm_gem_atomic_helper.h>
>> #include <drm/drm_gem_dma_helper.h>
>> #include <drm/drm_gem_framebuffer_helper.h>
>> #include <drm/drm_module.h>
>> #include <drm/drm_of.h>
>> #include <drm/drm_probe_helper.h>
>> -#include <drm/drm_simple_kms_helper.h>
>> #include <linux/dma-mapping.h>
>> #include <linux/module.h>
>> #include <linux/of_reserved_mem.h>
>> @@ -52,14 +52,14 @@ struct arcpgu_drm_private {
>> struct drm_device drm;
>> void __iomem *regs;
>> struct clk *clk;
>> - struct drm_simple_display_pipe pipe;
>> + struct drm_plane plane;
>> + struct drm_crtc crtc;
>> + struct drm_encoder encoder;
>> struct drm_connector sim_conn;
>> };
>>
>> #define dev_to_arcpgu(x) container_of(x, struct arcpgu_drm_private, drm)
>>
>> -#define pipe_to_arcpgu_priv(x) container_of(x, struct arcpgu_drm_private,
>> pipe)
>> -
>> static inline void arc_pgu_write(struct arcpgu_drm_private *arcpgu,
>> unsigned int reg, u32 value)
>> {
>> @@ -117,7 +117,7 @@ static const u32 arc_pgu_supported_formats[] = {
>>
>> static void arc_pgu_set_pxl_fmt(struct arcpgu_drm_private *arcpgu)
>> {
>> - const struct drm_framebuffer *fb = arcpgu->pipe.plane.state->fb;
>> + const struct drm_framebuffer *fb = arcpgu->plane.state->fb;
>> uint32_t pixel_format = fb->format->format;
>> u32 format = DRM_FORMAT_INVALID;
>> int i;
>> @@ -139,10 +139,10 @@ static void arc_pgu_set_pxl_fmt(struct
>> arcpgu_drm_private *arcpgu)
>> arc_pgu_write(arcpgu, ARCPGU_REG_CTRL, reg_ctrl);
>> }
>>
>> -static enum drm_mode_status arc_pgu_mode_valid(struct
>> drm_simple_display_pipe *pipe,
>> - const struct drm_display_mode
>> *mode)
>> +static enum drm_mode_status arcpgu_crtc_helper_mode_valid(struct drm_crtc
>> *crtc,
>> + const struct
>> drm_display_mode *mode)
>> {
>> - struct arcpgu_drm_private *arcpgu = pipe_to_arcpgu_priv(pipe);
>> + struct arcpgu_drm_private *arcpgu = dev_to_arcpgu(crtc->dev);
>> long rate, clk_rate = mode->clock * 1000;
>> long diff = clk_rate / 200; /* +-0.5% allowed by HDMI spec */
>>
>> @@ -155,7 +155,7 @@ static enum drm_mode_status arc_pgu_mode_valid(struct
>> drm_simple_display_pipe *p
>>
>> static void arc_pgu_mode_set(struct arcpgu_drm_private *arcpgu)
>> {
>> - struct drm_display_mode *m = &arcpgu->pipe.crtc.state->adjusted_mode;
>> + struct drm_display_mode *m = &arcpgu->crtc.state->adjusted_mode;
>> u32 val;
>>
>> arc_pgu_write(arcpgu, ARCPGU_REG_FMT,
>> @@ -194,11 +194,10 @@ static void arc_pgu_mode_set(struct arcpgu_drm_private
>> *arcpgu)
>> clk_set_rate(arcpgu->clk, m->crtc_clock * 1000);
>> }
>>
>> -static void arc_pgu_enable(struct drm_simple_display_pipe *pipe,
>> - struct drm_crtc_state *crtc_state,
>> - struct drm_plane_state *plane_state)
>> +static void arcpgu_crtc_helper_atomic_enable(struct drm_crtc *crtc,
>> + struct drm_atomic_commit *state)
>
> Since you're adding these functions anew, please use 'commit' for the
> name of the drm_atomic_commit. Here and everywhere else in the series.
> You don't have to update existing functions, of course.
>
> The name 'state' is a bit off here and comes from when drm_atomic_commit
> was still called drm_atomic_state.
>
> CRTCs, plane, etc have state, but the update of these states is called
> commit.
>
Thanks for your explanation.
I will change to name 'commit' for type drm_atomic_commit, here and
everywhere else in the series.
>
>> {
>> - struct arcpgu_drm_private *arcpgu = pipe_to_arcpgu_priv(pipe);
>> + struct arcpgu_drm_private *arcpgu = dev_to_arcpgu(crtc->dev);
>>
>> arc_pgu_mode_set(arcpgu);
>>
>> @@ -208,9 +207,10 @@ static void arc_pgu_enable(struct
>> drm_simple_display_pipe *pipe,
>> ARCPGU_CTRL_ENABLE_MASK);
>> }
>>
>> -static void arc_pgu_disable(struct drm_simple_display_pipe *pipe)
>> +static void arcpgu_crtc_helper_atomic_disable(struct drm_crtc *crtc,
>> + struct drm_atomic_commit *state)
>> {
>> - struct arcpgu_drm_private *arcpgu = pipe_to_arcpgu_priv(pipe);
>> + struct arcpgu_drm_private *arcpgu = dev_to_arcpgu(crtc->dev);
>>
>> clk_disable_unprepare(arcpgu->clk);
>> arc_pgu_write(arcpgu, ARCPGU_REG_CTRL,
>> @@ -218,35 +218,106 @@ static void arc_pgu_disable(struct
>> drm_simple_display_pipe *pipe)
>> ~ARCPGU_CTRL_ENABLE_MASK);
>> }
>>
>> -static void arc_pgu_update(struct drm_simple_display_pipe *pipe,
>> - struct drm_plane_state *state)
>> +static void arcpgu_plane_helper_atomic_update(struct drm_plane *plane,
>> + struct drm_atomic_commit *state)
>> {
>> struct arcpgu_drm_private *arcpgu;
>> struct drm_gem_dma_object *gem;
>>
>> - if (!pipe->plane.state->fb)
>> + if (!plane->state->fb)
>> return;
>>
>> - arcpgu = pipe_to_arcpgu_priv(pipe);
>> - gem = drm_fb_dma_get_gem_obj(pipe->plane.state->fb, 0);
>> + arcpgu = dev_to_arcpgu(plane->dev);
>> + gem = drm_fb_dma_get_gem_obj(plane->state->fb, 0);
>> arc_pgu_write(arcpgu, ARCPGU_REG_BUF0_ADDR, gem->dma_addr);
>> }
>>
>> -static const struct drm_simple_display_pipe_funcs arc_pgu_pipe_funcs = {
>> - .update = arc_pgu_update,
>> - .mode_valid = arc_pgu_mode_valid,
>> - .enable = arc_pgu_enable,
>> - .disable = arc_pgu_disable,
>> -};
>> -
>> static const struct drm_mode_config_funcs arcpgu_drm_modecfg_funcs = {
>> - .fb_create = drm_gem_fb_create,
>> + .fb_create = drm_gem_fb_create,
>> .atomic_check = drm_atomic_helper_check,
>> .atomic_commit = drm_atomic_helper_commit,
>> };
>>
>> DEFINE_DRM_GEM_DMA_FOPS(arcpgu_drm_ops);
>>
>> +static int arcpgu_plane_helper_atomic_check(struct drm_plane *plane,
>> + struct drm_atomic_commit *state)
>> +{
>> + struct drm_plane_state *plane_state =
>> drm_atomic_get_new_plane_state(state, plane);
>> + struct drm_crtc *crtc = plane_state->crtc;
>> + struct drm_crtc_state *crtc_state = NULL;
>> + int ret;
>> +
>> + if (crtc)
>> + crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
>> +
>> + ret = drm_atomic_helper_check_plane_state(plane_state, crtc_state,
>> + DRM_PLANE_NO_SCALING,
>> + DRM_PLANE_NO_SCALING,
>> + false, false);
>> + return ret;
>
>
> Return directly here.
>
OK
>
>> +}
>> +
>> +static const struct drm_plane_helper_funcs arcpgu_plane_helper_funcs = {
>> + .prepare_fb = drm_gem_plane_helper_prepare_fb,
>> + .atomic_check = arcpgu_plane_helper_atomic_check,
>> + .atomic_update = arcpgu_plane_helper_atomic_update,
>> +};
>> +
>> +static bool arcpgu_plane_format_mod_supported(struct drm_plane *plane,
>> + u32 format,
>> + u64 modifier)
>> +{
>> + return modifier == DRM_FORMAT_MOD_LINEAR;
>> +}
>
> Please remove this function. It doesn't really do anything besides DRM's
> standard behavior.
>
Will do
>> +
>> +static const struct drm_plane_funcs arcpgu_plane_funcs = {
>> + .update_plane = drm_atomic_helper_update_plane,
>> + .disable_plane = drm_atomic_helper_disable_plane,
>> + .destroy = drm_plane_cleanup,
>> + .reset = drm_atomic_helper_plane_reset,
>> + .atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state,
>> + .atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
>> + .format_mod_supported = arcpgu_plane_format_mod_supported,
>> +};
>> +
>> +static int arcpgu_crtc_helper_atomic_check(struct drm_crtc *crtc,
>> + struct drm_atomic_commit *state)
>> +{
>> + struct drm_crtc_state *crtc_state =
>> drm_atomic_get_new_crtc_state(state, crtc);
>> + int ret;
>> +
>> + if (!crtc_state->enable)
>> + goto out;
>> +
>> + ret = drm_atomic_helper_check_crtc_primary_plane(crtc_state);
>> + if (ret)
>> + return ret;
>> +
>> +out:
>> + return drm_atomic_add_affected_planes(state, crtc);
>
> Instead of using out, I'd rather use
>
> if (crtc->enable) {
> //do checks
> }
>
> return add_affected planes.
>
> Seems more natural to me.
>
Will do
>> +}
>> +
>> +static const struct drm_crtc_helper_funcs arcpgu_crtc_helper_funcs = {
>> + .mode_valid = arcpgu_crtc_helper_mode_valid,
>> + .atomic_check = arcpgu_crtc_helper_atomic_check,
>> + .atomic_enable = arcpgu_crtc_helper_atomic_enable,
>> + .atomic_disable = arcpgu_crtc_helper_atomic_disable,
>> +};
>> +
>> +static const struct drm_crtc_funcs arcpgu_crtc_funcs = {
>> + .reset = drm_atomic_helper_crtc_reset,
>> + .destroy = drm_crtc_cleanup,
>> + .set_config = drm_atomic_helper_set_config,
>> + .page_flip = drm_atomic_helper_page_flip,
>> + .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
>> + .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
>> +};
>> +
>> +static const struct drm_encoder_funcs arcpgu_encoder_funcs = {
>> + .destroy = drm_encoder_cleanup,
>> +};
>> +
>> static int arcpgu_load(struct arcpgu_drm_private *arcpgu)
>> {
>> struct platform_device *pdev = to_platform_device(arcpgu->drm.dev);
>> @@ -254,6 +325,9 @@ static int arcpgu_load(struct arcpgu_drm_private *arcpgu)
>> struct device_node *endpoint_node = NULL;
>> struct drm_connector *connector = NULL;
>> struct drm_device *drm = &arcpgu->drm;
>> + struct drm_plane *plane;
>> + struct drm_encoder *encoder;
>> + struct drm_crtc *crtc;
>> int ret;
>>
>> arcpgu->clk = devm_clk_get(drm->dev, "pxlclk");
>> @@ -301,12 +375,35 @@ static int arcpgu_load(struct arcpgu_drm_private
>> *arcpgu)
>> return ret;
>> }
>>
>> - ret = drm_simple_display_pipe_init(drm, &arcpgu->pipe,
>> &arc_pgu_pipe_funcs,
>> - arc_pgu_supported_formats,
>> -
>> ARRAY_SIZE(arc_pgu_supported_formats),
>> - NULL, connector);
>> + plane = &arcpgu->plane;
>> + ret = drm_universal_plane_init(drm, plane, 0,
>> + &arcpgu_plane_funcs,
>> + arc_pgu_supported_formats,
>> + ARRAY_SIZE(arc_pgu_supported_formats),
>> + NULL,
>> + DRM_PLANE_TYPE_PRIMARY, NULL);
>> if (ret)
>> return ret;
>> + drm_plane_helper_add(plane, &arcpgu_plane_helper_funcs);
>> +
>> + crtc = &arcpgu->crtc;
>> + ret = drm_crtc_init_with_planes(drm, crtc, plane, NULL,
>> + &arcpgu_crtc_funcs, NULL);
>> + if (ret)
>> + return ret;
>> + drm_crtc_helper_add(crtc, &arcpgu_crtc_helper_funcs);
>> +
>> + encoder = &arcpgu->encoder;
>> + ret = drm_encoder_init(drm, encoder, &arcpgu_encoder_funcs,
>> DRM_MODE_ENCODER_NONE, NULL);
>> + if (ret)
>> + return ret;
>> + encoder->possible_crtcs = drm_crtc_mask(crtc);
>
>
> I think plane, CRTC, and encoder should go before testing the
> encoder_node at [1].
>
> Then comes the encoder_node test. If true, do a single encoder-node
> branch, or else to a single connector-based branch. That would
> simplify the overall logic in this helper.
>
> [1]
> https://elixir.bootlin.com/linux/v7.1.2/source/drivers/gpu/drm/tiny/arcpgu.c#L287
>
OK, will move them before the encoder_node test
>
>> +
>> + if (connector) {
>> + ret = drm_connector_attach_encoder(connector, encoder);
>> + if (ret)
>> + return ret;
>> + }
>>
>> if (encoder_node) {
>> /* Locate drm bridge from the hdmi encoder DT node */
>> @@ -315,7 +412,7 @@ static int arcpgu_load(struct arcpgu_drm_private *arcpgu)
>> if (!bridge)
>> return -EPROBE_DEFER;
>>
>> - ret = drm_simple_display_pipe_attach_bridge(&arcpgu->pipe,
>> bridge);
>> + ret = drm_bridge_attach(encoder, bridge, NULL, 0);
>> if (ret)
>> return ret;
>> }
>> @@ -342,7 +439,7 @@ static int arcpgu_show_pxlclock(struct seq_file *m, void
>> *arg)
>> struct drm_device *drm = node->minor->dev;
>> struct arcpgu_drm_private *arcpgu = dev_to_arcpgu(drm);
>> unsigned long clkrate = clk_get_rate(arcpgu->clk);
>> - unsigned long mode_clock = arcpgu->pipe.crtc.mode.crtc_clock * 1000;
>> + unsigned long mode_clock = arcpgu->crtc.mode.crtc_clock * 1000;
>
> Here, mode is an obsolete field. The correct field is crtc->state->mode.
Will correct the field
>
> Best regards
> Thomas
>
>>
>> seq_printf(m, "hw : %lu\n", clkrate);
>> seq_printf(m, "mode: %lu\n", mode_clock);
>>
Thanks,
Ze
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