linux-kernel - [PATCH v4 9/9] drm/mediatek: Add cmdq_insert_backup

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Date: Wed, 3 Apr 2024 15:07:32 +0800
From: Shawn Sung <shawn.sung@...iatek.com>
To: Chun-Kuang Hu <chunkuang.hu@...nel.org>
CC: Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>, Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	"Maarten Lankhorst" <maarten.lankhorst@...ux.intel.com>, Maxime Ripard
	<mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, Sumit Semwal
	<sumit.semwal@...aro.org>, Christian König
	<christian.koenig@....com>, <dri-devel@...ts.freedesktop.org>,
	<linux-mediatek@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-media@...r.kernel.org>,
	<linaro-mm-sig@...ts.linaro.org>, Jason-JH.Lin <jason-jh.lin@...iatek.com>,
	Hsiao Chien Sung <shawn.sung@...iatek.com>
Subject: [PATCH v4 9/9] drm/mediatek: Add cmdq_insert_backup_cookie before secure pkt finalize

From: "Jason-JH.Lin" <jason-jh.lin@...iatek.com>

Add cmdq_insert_backup_cookie to append some commands before EOC:
1. Get GCE HW thread execute count from the GCE HW register.
2. Add 1 to the execute count and then store into a shared memory.
3. Set a software event siganl as secure irq to GCE HW.

Since the value of execute count + 1 is stored in a shared memory,
CMDQ driver in the normal world can use it to handle task done in irq
handler and CMDQ driver in the secure world will use it to schedule
the task slot for each secure thread.

The reason why we use shared memory to record execute count here is:
1. normal world can not access the register of secure GCE thread in
normal world.
2. calling TEE invoke cmd in the irq handler would be expensive and not
stable. I've tested that a single TEE invloke cmd to CMDQ PTA costs
19~53 us. Maybe it would cost more during the scenario that needs more
CPU loading.

Signed-off-by: Jason-JH.Lin <jason-jh.lin@...iatek.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@...iatek.com>
---
 drivers/gpu/drm/mediatek/mtk_crtc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_crtc.c b/drivers/gpu/drm/mediatek/mtk_crtc.c
index a6ba9965500f0..2fb52928a3055 100644
--- a/drivers/gpu/drm/mediatek/mtk_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_crtc.c
@@ -186,7 +186,7 @@ void mtk_crtc_disable_secure_state(struct drm_crtc *crtc)
 		sec_scn = CMDQ_SEC_SCNR_SUB_DISP_DISABLE;
 
 	cmdq_sec_pkt_set_data(&mtk_crtc->sec_cmdq_handle, sec_engine, sec_engine, sec_scn);
-
+	cmdq_sec_insert_backup_cookie(&mtk_crtc->sec_cmdq_handle);
 	cmdq_pkt_finalize(&mtk_crtc->sec_cmdq_handle);
 	dma_sync_single_for_device(mtk_crtc->sec_cmdq_client.chan->mbox->dev,
 				   mtk_crtc->sec_cmdq_handle.pa_base,
@@ -810,6 +810,8 @@ static void mtk_crtc_update_config(struct mtk_crtc *mtk_crtc, bool needs_vblank)
 		cmdq_pkt_clear_event(cmdq_handle, mtk_crtc->cmdq_event);
 		cmdq_pkt_wfe(cmdq_handle, mtk_crtc->cmdq_event, false);
 		mtk_crtc_ddp_config(crtc, cmdq_handle);
+		if (cmdq_handle->sec_data)
+			cmdq_sec_insert_backup_cookie(cmdq_handle);
 		cmdq_pkt_finalize(cmdq_handle);
 		dma_sync_single_for_device(cmdq_client.chan->mbox->dev,
 					   cmdq_handle->pa_base,
-- 
2.18.0