Re: [PATCH v3 6/6] drm/mediatek: apply CMDQ control flow

CK Hu
2019-12-05T05:45:18Z

Hi, Bibby:

On Wed, 2019-12-04 at 17:44 +0800, Bibby Hsieh wrote:
> Unlike other SoCs, MT8183 does not have "shadow"
> registers for performaing an atomic video mode
> set or page flip at vblank/vsync.
>
> The CMDQ (Commend Queue) in MT8183 is used to help
> update all relevant display controller registers
> with critical time limation.
>
> Signed-off-by: YT Shen <yt.shen@mediatek.com>
> Signed-off-by: CK Hu <ck.hu@mediatek.com>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
> Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
> ---
> drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 80 ++++++++++++++++++++++++-
> 1 file changed, 77 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> index 9f1ff2f3f104..9340346e2727 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
> @@ -12,6 +12,8 @@
> #include <drm/drm_plane_helper.h>
> #include <drm/drm_probe_helper.h>
> #include <drm/drm_vblank.h>
> +#include <linux/of_address.h>
> +#include <linux/soc/mediatek/mtk-cmdq.h>
>
> #include "mtk_drm_drv.h"
> #include "mtk_drm_crtc.h"
> @@ -42,6 +44,9 @@ struct mtk_drm_crtc {
> unsigned int layer_nr;
> bool pending_planes;
>
> + struct cmdq_client *cmdq_client;
> + u32 cmdq_event;
> +
> void __iomem *config_regs;
> const struct mtk_mmsys_reg_data *mmsys_reg_data;
> struct mtk_disp_mutex *mutex;
> @@ -59,6 +64,11 @@ struct mtk_crtc_state {
> unsigned int pending_width;
> unsigned int pending_height;
> unsigned int pending_vrefresh;
> + struct cmdq_pkt *cmdq_handle;

The handle is just used in mtk_drm_crtc_hw_config(), so I think you need
not to store it in mtk_crtc_state. Make it a local variable in
mtk_drm_crtc_hw_config() is enough.

> +};
> +
> +struct mtk_cmdq_cb_data {
> + struct cmdq_pkt *cmdq_handle;
> };
>
> static inline struct mtk_drm_crtc *to_mtk_crtc(struct drm_crtc *c)
> @@ -233,6 +243,47 @@ struct mtk_ddp_comp *mtk_drm_ddp_comp_for_plane(struct drm_crtc *crtc,
> return NULL;
> }
>
> +#ifdef CONFIG_MTK_CMDQ
> +static void ddp_cmdq_cb(struct cmdq_cb_data data)
> +{
> + struct mtk_cmdq_cb_data *cb_data = data.data;
> +
> + cmdq_pkt_destroy(cb_data->cmdq_handle);
> + kfree(cb_data);
> +}
> +
> +static void mtk_cmdq_acquire(struct drm_crtc *crtc)
> +{
> + struct mtk_crtc_state *mtk_crtc_state =
> + to_mtk_crtc_state(crtc->state);
> + struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> +
> + mtk_crtc_state->cmdq_handle =
> + cmdq_pkt_create(mtk_crtc->cmdq_client,
> + PAGE_SIZE);
> + cmdq_pkt_clear_event(mtk_crtc_state->cmdq_handle,
> + mtk_crtc->cmdq_event);
> + cmdq_pkt_wfe(mtk_crtc_state->cmdq_handle, mtk_crtc->cmdq_event);
> +}
> +
> +static void mtk_cmdq_release(struct drm_crtc *crtc)
> +{
> + struct mtk_crtc_state *mtk_crtc_state =
> + to_mtk_crtc_state(crtc->state);
> + struct mtk_cmdq_cb_data *cb_data;
> +
> + cb_data = kmalloc(sizeof(*cb_data), GFP_KERNEL);
> + if (!cb_data) {
> + DRM_DEV_ERROR(crtc->dev->dev, "Failed to alloc cb_data\n");
> + return;
> + }
> +
> + cb_data->cmdq_handle = mtk_crtc_state->cmdq_handle;
> + cmdq_pkt_flush_async(mtk_crtc_state->cmdq_handle,
> + ddp_cmdq_cb, cb_data);

Why do you create mtk_cmdq_cb_data{}? You could directly put handle in
cb_date parameter.

> +}
> +#endif
> +
> static int mtk_crtc_ddp_hw_init(struct mtk_drm_crtc *mtk_crtc)
> {
> struct drm_crtc *crtc = &mtk_crtc->base;
> @@ -393,7 +444,8 @@ static void mtk_crtc_ddp_config(struct drm_crtc *crtc)
> if (state->pending_config) {
> mtk_ddp_comp_config(comp, state->pending_width,
> state->pending_height,
> - state->pending_vrefresh, 0, NULL);
> + state->pending_vrefresh, 0,
> + state->cmdq_handle);
>
> state->pending_config = false;
> }
> @@ -413,7 +465,8 @@ static void mtk_crtc_ddp_config(struct drm_crtc *crtc)
>
> if (comp)
> mtk_ddp_comp_layer_config(comp, local_layer,
> - plane_state, NULL);
> + plane_state,
> + state->cmdq_handle);
> plane_state->pending.config = false;
> }
> mtk_crtc->pending_planes = false;
> @@ -452,6 +505,13 @@ static void mtk_drm_crtc_hw_config(struct mtk_drm_crtc *mtk_crtc)
> mtk_crtc_ddp_config(crtc);
> mtk_disp_mutex_release(mtk_crtc->mutex);
> }
> +#ifdef CONFIG_MTK_CMDQ
> + if (mtk_crtc->cmdq_client) {
> + mtk_cmdq_acquire(crtc);
> + mtk_crtc_ddp_config(crtc);
> + mtk_cmdq_release(crtc);
> + }
> +#endif
> mutex_unlock(&mtk_crtc->hw_lock);
> }
>
> @@ -528,6 +588,7 @@ static void mtk_drm_crtc_atomic_disable(struct drm_crtc *crtc,
> mtk_crtc->pending_planes = true;
>
> /* Wait for planes to be disabled */
> + mtk_drm_crtc_hw_config(mtk_crtc);

I think shadow register has the same problem, so I would like to move
this part to an independent patch which fix shadow register problem. And
I think this statement should be moved before the comment because this
statement does not doing wait.

> drm_crtc_wait_one_vblank(crtc);
>
> drm_crtc_vblank_off(crtc);
> @@ -619,7 +680,7 @@ void mtk_crtc_ddp_irq(struct drm_crtc *crtc, struct mtk_ddp_comp *comp)
> struct mtk_drm_crtc *mtk_crtc = to_mtk_crtc(crtc);
> struct mtk_drm_private *priv = crtc->dev->dev_private;
>
> - if (!priv->data->shadow_register)
> + if (!priv->data->shadow_register && !mtk_crtc->cmdq_client)
> mtk_crtc_ddp_config(crtc);
>
> mtk_drm_finish_page_flip(mtk_crtc);
> @@ -763,5 +824,18 @@ int mtk_drm_crtc_create(struct drm_device *drm_dev,
> priv->num_pipes++;
> mutex_init(&mtk_crtc->hw_lock);
>
> +#ifdef CONFIG_MTK_CMDQ
> + mtk_crtc->cmdq_client =
> + cmdq_mbox_create(dev, drm_crtc_index(&mtk_crtc->base),
> + 2000);
> + of_property_read_u32_index(dev->of_node, "mediatek,gce-events",
> + drm_crtc_index(&mtk_crtc->base),
> + &mtk_crtc->cmdq_event);

Check the return value.

Regards,
CK

> + if (IS_ERR(mtk_crtc->cmdq_client)) {
> + dev_dbg(dev, "mtk_crtc %d failed to create mailbox client, writing register by CPU now\n",
> + drm_crtc_index(&mtk_crtc->base));
> + mtk_crtc->cmdq_client = NULL;
> + }
> +#endif
> return 0;
> }