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Message-ID: <bb6683011afc9febc64946e9dcae102ca5ba0054.camel@mediatek.com>
Date: Wed, 24 Apr 2024 09:14:30 +0000
From: Shuijing Li (李水静) <Shuijing.Li@...iatek.com>
To: "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>, "airlied@...il.com"
	<airlied@...il.com>, "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
	"daniel@...ll.ch" <daniel@...ll.ch>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>, "chunkuang.hu@...nel.org"
	<chunkuang.hu@...nel.org>, Jitao Shi (石记涛)
	<jitao.shi@...iatek.com>
CC: "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, Project_Global_Chrome_Upstream_Group
	<Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH] mediatek: dsi: Add dsi per-frame lp code for mt8188

Dear Angelo,

> Please document those "magic numbers": why is this 12 + 2 + 4 ?
> What is 12? what is 2? what is 4?
==>
This is several packets, as specified in chapter 8.11 of the DSI
specification. Taking this as an example, 12 = 4 (HSS) + 4 (HSA_PH) + 4
(HSE), 2 = HSA_PF, and 4 = HBP_PH.

> Is this supported only on MT8188? Are you sure that MT8195 doesn't
> support that?
==>
MT8195 does not have this plan.

Based on the feedback you provided, I have made the necessary changes
and would like to submit a version 2 for your consideration at a later
date.

Thank you for your time and attention to this matter.


Best regards,
Shuijing

On Thu, 2024-03-14 at 11:10 +0100, AngeloGioacchino Del Regno wrote:
> Il 14/03/24 10:41, Shuijing Li ha scritto:
> > Adding the per-frame lp function of mt8188, which can keep HFP in
> > HS and
> > reduce the time required for each line to enter and exit low power.
> > Per Frame LP:
> >    |<----------One Active Frame-------->|
> > --______________________________________----___________________
> >    ^HSA+HBP^^RGB^^HFP^^HSA+HBP^^RGB^^HFP^    ^HSA+HBP^^RGB^^HFP^
> > 
> > Per Line LP:
> >    |<---------------One Active Frame----------->|
> > --______________--______________--______________----______________
> >    ^HSA+HBP^^RGB^  ^HSA+HBP^^RGB^  ^HSA+HBP^^RGB^    ^HSA+HBP^^RGB^
> > 
> > Signed-off-by: Shuijing Li <shuijing.li@...iatek.com>
> > ---
> >   drivers/gpu/drm/mediatek/mtk_dsi.c | 100
> > +++++++++++++++++++++++++++++
> >   1 file changed, 100 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > index a2fdfc8ddb15..e6f4807c8711 100644
> > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> > @@ -83,6 +83,7 @@
> >   #define DSI_HSA_WC		0x50
> >   #define DSI_HBP_WC		0x54
> >   #define DSI_HFP_WC		0x58
> > +#define DSI_BLLP_WC		0x5C
> >   
> >   #define DSI_CMDQ_SIZE		0x60
> >   #define CMDQ_SIZE			0x3f
> > @@ -180,6 +181,7 @@ struct mtk_dsi_driver_data {
> >   	bool has_shadow_ctl;
> >   	bool has_size_ctl;
> >   	bool cmdq_long_packet_ctl;
> > +	bool support_per_frame_lp;
> >   };
> >   
> >   struct mtk_dsi {
> > @@ -516,6 +518,103 @@ static void mtk_dsi_config_vdo_timing(struct
> > mtk_dsi *dsi)
> >   			(vm->hactive * dsi_tmp_buf_bpp + 2) % dsi-
> > >lanes;
> >   	}
> >   
> > +	if (dsi->driver_data->support_per_frame_lp) {
> 
> This really looks like a good candidate to fit in a function on its
> own...
> 
> > +		unsigned int lpx = 0, da_hs_exit = 0, da_hs_prep = 0,
> > da_hs_trail = 0;
> > +		unsigned int da_hs_zero = 0, ps_wc = 0, hs_vb_ps_wc =
> > 0;
> > +		u32 bllp_wc, bllp_en, v_active_roundup, hstx_cklp_wc;
> > +		u32 hstx_cklp_wc_max, hstx_cklp_wc_min;
> > +
> > +		da_hs_trail = (readl(dsi->regs + DSI_PHY_TIMECON0) >>
> > 24) & 0xff;
> > +		bllp_en = (readl(dsi->regs + DSI_TXRX_CTRL) >> 7) &
> > 0x1;
> 
> (somewhere: #define HSTX_BLLP_EN BIT(7))
> 
> u32 timecon0, txrx_ctrl;
> 
> timecon0 = readl(....DSI_PHY_TIMECON0);
> txrx_ctrl = readl(.....);
> 
> da_hs_trail = FIELD_GET(HS_TRAIL, timecon0);
> bllp_en = FIELD_GET(HSTX_BLLP_EN, txrx_ctrl);
> 
> > +		if (dsi->mode_flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) {
> > +			horizontal_sync_active_byte =
> > +				(vm->hsync_len * dsi_tmp_buf_bpp - 10);
> > +			horizontal_backporch_byte =
> > +				(vm->hback_porch * dsi_tmp_buf_bpp -
> > 10);
> > +			horizontal_frontporch_byte =
> > +				(vm->hfront_porch * dsi_tmp_buf_bpp -
> > 12);
> > +
> > +			ps_wc = readl(dsi->regs + DSI_PSCTRL) & 0x7fff;
> > +			v_active_roundup = (32 +
> > horizontal_sync_active_byte +
> > +				horizontal_backporch_byte + ps_wc +
> > +				horizontal_frontporch_byte) % dsi-
> > >lanes;
> > +			if (v_active_roundup)
> > +				horizontal_backporch_byte =
> > horizontal_backporch_byte +
> > +					dsi->lanes - v_active_roundup;
> > +			hstx_cklp_wc_min = (DIV_ROUND_UP((12 + 2 + 4 +
> 
> Please document those "magic numbers": why is this 12 + 2 + 4 ?
> What is 12? what is 2? what is 4?
> 
> > +				horizontal_sync_active_byte), dsi-
> > >lanes) + da_hs_trail + 1)
> > +				* dsi->lanes / 6 - 1;
> > +			hstx_cklp_wc_max = (DIV_ROUND_UP((20 + 6 + 4 +
> > +				horizontal_sync_active_byte +
> > horizontal_backporch_byte +
> > +				ps_wc), dsi->lanes) + da_hs_trail + 1)
> > * dsi->lanes / 6 - 1;
> > +		} else {
> > +			horizontal_sync_active_byte = vm->hsync_len *
> > dsi_tmp_buf_bpp - 4;
> > +
> > +			horizontal_backporch_byte = (vm->hback_porch +
> > vm->hsync_len) *
> > +				dsi_tmp_buf_bpp - 10;
> > +			hstx_cklp_wc_min = (DIV_ROUND_UP(4, dsi->lanes) 
> > + da_hs_trail + 1)
> > +				* dsi->lanes / 6 - 1;
> > +
> > +			if (dsi->mode_flags &
> > MIPI_DSI_MODE_VIDEO_BURST) {
> > +				ps_wc = readl(dsi->regs + DSI_PSCTRL) &
> > 0x7fff;
> > +				bllp_wc = readl(dsi->regs +
> > DSI_BLLP_WC) & 0xfff;
> 
> Please use bitfield macros here as well.
> 
> > +				horizontal_frontporch_byte = (vm-
> > >hfront_porch *
> > +					dsi_tmp_buf_bpp - 18);
> > +
> > +				v_active_roundup = (28 +
> > horizontal_backporch_byte + ps_wc +
> > +					horizontal_frontporch_byte +
> > bllp_wc) % dsi->lanes;
> > +				if (v_active_roundup)
> > +					horizontal_backporch_byte =
> > horizontal_backporch_byte +
> > +					dsi->lanes - v_active_roundup;
> > +				if (bllp_en) {
> > +					hstx_cklp_wc_max =
> > (DIV_ROUND_UP((16 + 6 + 4 +
> > +						horizontal_backporch_by
> > te + bllp_wc + ps_wc),
> > +						dsi->lanes) +
> > da_hs_trail + 1) * dsi->lanes / 6 - 1;
> > +				} else {
> > +					hstx_cklp_wc_max =
> > (DIV_ROUND_UP((12 + 4 + 4 +
> > +						horizontal_backporch_by
> > te + bllp_wc + ps_wc),
> > +						dsi->lanes) +
> > da_hs_trail + 1) * dsi->lanes / 6 - 1;
> > +				}
> > +			} else {
> > +				ps_wc = readl(dsi->regs + DSI_PSCTRL) &
> > 0x7fff;
> > +				horizontal_frontporch_byte = (vm-
> > >hfront_porch *
> > +					dsi_tmp_buf_bpp - 12);
> > +
> > +				v_active_roundup = (22 +
> > horizontal_backporch_byte + ps_wc +
> > +					horizontal_frontporch_byte) %
> > dsi->lanes;
> > +				if (v_active_roundup)
> > +					horizontal_backporch_byte =
> > horizontal_backporch_byte +
> > +					dsi->lanes - v_active_roundup;
> > +
> > +				hstx_cklp_wc_max = (DIV_ROUND_UP((12 +
> > 4 + 4 +
> > +					horizontal_backporch_byte +
> > ps_wc),
> > +					dsi->lanes) + da_hs_trail + 1)
> > * dsi->lanes / 6 - 1;
> > +			}
> > +		}
> > +		hstx_cklp_wc = (readl(dsi->regs + DSI_HSTX_CKL_WC) >>
> > 2) & 0x3fff;
> 
> same here
> 
> > +		if (hstx_cklp_wc <= hstx_cklp_wc_min ||
> > +			hstx_cklp_wc >= hstx_cklp_wc_max) {
> > +			hstx_cklp_wc = (hstx_cklp_wc_max / 2) << 2;
> 
> and same here... and everywhere else.
> 
> > +			writel(hstx_cklp_wc, dsi->regs +
> > DSI_HSTX_CKL_WC);
> > +		}
> > +		hstx_cklp_wc = hstx_cklp_wc >> 2;
> > +		if (hstx_cklp_wc <= hstx_cklp_wc_min ||
> > +			hstx_cklp_wc >= hstx_cklp_wc_max) {
> > +			DRM_WARN("Wrong setting of hstx_ckl_wc\n");
> > +		}
> > +
> > +		lpx = readl(dsi->regs + DSI_PHY_TIMECON0) & 0xff;
> > +		da_hs_exit = (readl(dsi->regs + DSI_PHY_TIMECON1) >>
> > 24) & 0xff;
> > +		da_hs_prep = (readl(dsi->regs + DSI_PHY_TIMECON0) >> 8)
> > & 0xff;
> > +		da_hs_zero = (readl(dsi->regs + DSI_PHY_TIMECON0) >>
> > 16) & 0xff;
> > +		ps_wc = readl(dsi->regs + DSI_PSCTRL) & 0x7fff;
> > +		hs_vb_ps_wc = ps_wc -
> > +			(lpx + da_hs_exit + da_hs_prep + da_hs_zero +
> > 2)
> > +			* dsi->lanes;
> > +		horizontal_frontporch_byte = (1 << 31)
> > +			| (hs_vb_ps_wc << 16)
> > +			| (horizontal_frontporch_byte);
> > +	}
> >   	writel(horizontal_sync_active_byte, dsi->regs + DSI_HSA_WC);
> >   	writel(horizontal_backporch_byte, dsi->regs + DSI_HBP_WC);
> >   	writel(horizontal_frontporch_byte, dsi->regs + DSI_HFP_WC);
> > @@ -1246,6 +1345,7 @@ static const struct mtk_dsi_driver_data
> > mt8188_dsi_driver_data = {
> >   	.has_shadow_ctl = true,
> >   	.has_size_ctl = true,
> >   	.cmdq_long_packet_ctl = true,
> > +	.support_per_frame_lp = true,
> 
> Is this supported only on MT8188? Are you sure that MT8195 doesn't
> support that?
> 
> Regards,
> Angelo
> 
> >   };
> >   
> >   static const struct of_device_id mtk_dsi_of_match[] = {
> 
> 

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