linux-kernel - [PATCH v3 10/11] drm/mediatek: Add cmdq_insert_backup

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Message-ID: <20231223182932.27683-11-jason-jh.lin@mediatek.com>
Date: Sun, 24 Dec 2023 02:29:31 +0800
From: Jason-JH.Lin <jason-jh.lin@...iatek.com>
To: Rob Herring <robh+dt@...nel.org>, Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>, Conor Dooley <conor+dt@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>, AngeloGioacchino Del Regno
	<angelogioacchino.delregno@...labora.com>, Chun-Kuang Hu
	<chunkuang.hu@...nel.org>
CC: <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-mediatek@...ts.infradead.org>,
	<dri-devel@...ts.freedesktop.org>, <linux-media@...r.kernel.org>,
	<linaro-mm-sig@...ts.linaro.org>, Jason-ch Chen <jason-ch.chen@...iatek.com>,
	Johnson Wang <johnson.wang@...iatek.com>, "Jason-JH . Lin"
	<jason-jh.lin@...iatek.com>, Singo Chang <singo.chang@...iatek.com>, Nancy
 Lin <nancy.lin@...iatek.com>, Shawn Sung <shawn.sung@...iatek.com>,
	<Project_Global_Chrome_Upstream_Group@...iatek.com>, Jeffrey Kardatzke
	<jkardatzke@...gle.com>
Subject: [PATCH v3 10/11] drm/mediatek: Add cmdq_insert_backup_cookie before secure pkt finalize

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>
---
 drivers/gpu/drm/mediatek/mtk_drm_crtc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
index 79617c0f016d..856513a14cda 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_crtc.c
@@ -179,7 +179,7 @@ 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,
@@ -791,6 +791,8 @@ static void mtk_drm_crtc_update_config(struct mtk_drm_crtc *mtk_crtc,
 		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