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Date:	Wed, 20 Jul 2016 15:15:02 +0800
From:	CK Hu <ck.hu@...iatek.com>
To:	Bibby Hsieh <bibby.hsieh@...iatek.com>
CC:	David Airlie <airlied@...ux.ie>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Daniel Vetter <daniel.vetter@...ll.ch>,
	<dri-devel@...ts.freedesktop.org>,
	<linux-mediatek@...ts.infradead.org>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Cawa Cheng <cawa.cheng@...iatek.com>,
	Daniel Kurtz <djkurtz@...omium.org>,
	"Philipp Zabel" <p.zabel@...gutronix.de>,
	YT Shen <yt.shen@...iatek.com>,
	"Thierry Reding" <thierry.reding@...il.com>,
	Mao Huang <littlecvr@...omium.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	"Sascha Hauer" <kernel@...gutronix.de>,
	Junzhi Zhao <junzhi.zhao@...iatek.com>
Subject: Re: [PATCH 2/4] drm/mediatek: enhance the HDMI driving current

Hi, Bibby:

One comment inline.

On Wed, 2016-07-20 at 12:03 +0800, Bibby Hsieh wrote:
> From: Junzhi Zhao <junzhi.zhao@...iatek.com>
> 
> In order to improve 4K resolution performance,
> we have to enhance the HDMI driving currend
> when clock rate is greater than 165MHz.
> 
> Signed-off-by: Junzhi Zhao <junzhi.zhao@...iatek.com>
> Signed-off-by: Bibby Hsieh <bibby.hsieh@...iatek.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c |   89 +++++++++++++++++-------
>  1 file changed, 63 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c b/drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c
> index 8a24754..a871c14 100644
> --- a/drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c
> +++ b/drivers/gpu/drm/mediatek/mtk_mt8173_hdmi_phy.c
> @@ -298,32 +298,69 @@ static int mtk_hdmi_pll_set_rate(struct clk_hw *hw, unsigned long rate,
>  			  (0x1 << PLL_BR_SHIFT),
>  			  RG_HDMITX_PLL_BP | RG_HDMITX_PLL_BC |
>  			  RG_HDMITX_PLL_BR);
> -	mtk_hdmi_phy_clear_bits(hdmi_phy, HDMI_CON3, RG_HDMITX_PRD_IMP_EN);
> -	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON4,
> -			  (0x3 << PRD_IBIAS_CLK_SHIFT) |
> -			  (0x3 << PRD_IBIAS_D2_SHIFT) |
> -			  (0x3 << PRD_IBIAS_D1_SHIFT) |
> -			  (0x3 << PRD_IBIAS_D0_SHIFT),
> -			  RG_HDMITX_PRD_IBIAS_CLK |
> -			  RG_HDMITX_PRD_IBIAS_D2 |
> -			  RG_HDMITX_PRD_IBIAS_D1 |
> -			  RG_HDMITX_PRD_IBIAS_D0);
> -	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON3,
> -			  (0x0 << DRV_IMP_EN_SHIFT), RG_HDMITX_DRV_IMP_EN);
> -	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON6,
> -			  (hdmi_phy->drv_imp_clk << DRV_IMP_CLK_SHIFT) |
> -			  (hdmi_phy->drv_imp_d2 << DRV_IMP_D2_SHIFT) |
> -			  (hdmi_phy->drv_imp_d1 << DRV_IMP_D1_SHIFT) |
> -			  (hdmi_phy->drv_imp_d0 << DRV_IMP_D0_SHIFT),
> -			  RG_HDMITX_DRV_IMP_CLK | RG_HDMITX_DRV_IMP_D2 |
> -			  RG_HDMITX_DRV_IMP_D1 | RG_HDMITX_DRV_IMP_D0);
> -	mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON5,
> -			  (hdmi_phy->ibias << DRV_IBIAS_CLK_SHIFT) |
> -			  (hdmi_phy->ibias << DRV_IBIAS_D2_SHIFT) |
> -			  (hdmi_phy->ibias << DRV_IBIAS_D1_SHIFT) |
> -			  (hdmi_phy->ibias << DRV_IBIAS_D0_SHIFT),
> -			  RG_HDMITX_DRV_IBIAS_CLK | RG_HDMITX_DRV_IBIAS_D2 |
> -			  RG_HDMITX_DRV_IBIAS_D1 | RG_HDMITX_DRV_IBIAS_D0);
> +	if (rate < 165000000) {
> +		mtk_hdmi_phy_clear_bits(hdmi_phy, HDMI_CON3,
> +					RG_HDMITX_PRD_IMP_EN);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON4,
> +				  (0x3 << PRD_IBIAS_CLK_SHIFT) |
> +				  (0x3 << PRD_IBIAS_D2_SHIFT) |
> +				  (0x3 << PRD_IBIAS_D1_SHIFT) |
> +				  (0x3 << PRD_IBIAS_D0_SHIFT),
> +				  RG_HDMITX_PRD_IBIAS_CLK |
> +				  RG_HDMITX_PRD_IBIAS_D2 |
> +				  RG_HDMITX_PRD_IBIAS_D1 |
> +				  RG_HDMITX_PRD_IBIAS_D0);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON3,
> +				  (0x0 << DRV_IMP_EN_SHIFT),
> +				  RG_HDMITX_DRV_IMP_EN);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON6,
> +				  (hdmi_phy->drv_imp_clk << DRV_IMP_CLK_SHIFT) |
> +				  (hdmi_phy->drv_imp_d2 << DRV_IMP_D2_SHIFT) |
> +				  (hdmi_phy->drv_imp_d1 << DRV_IMP_D1_SHIFT) |
> +				  (hdmi_phy->drv_imp_d0 << DRV_IMP_D0_SHIFT),
> +				  RG_HDMITX_DRV_IMP_CLK | RG_HDMITX_DRV_IMP_D2 |
> +				  RG_HDMITX_DRV_IMP_D1 | RG_HDMITX_DRV_IMP_D0);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON5,
> +				  (hdmi_phy->ibias << DRV_IBIAS_CLK_SHIFT) |
> +				  (hdmi_phy->ibias << DRV_IBIAS_D2_SHIFT) |
> +				  (hdmi_phy->ibias << DRV_IBIAS_D1_SHIFT) |
> +				  (hdmi_phy->ibias << DRV_IBIAS_D0_SHIFT),
> +				  RG_HDMITX_DRV_IBIAS_CLK |
> +				  RG_HDMITX_DRV_IBIAS_D2 |
> +				  RG_HDMITX_DRV_IBIAS_D1 |
> +				  RG_HDMITX_DRV_IBIAS_D0);
> +	} else {
> +		mtk_hdmi_phy_set_bits(hdmi_phy, HDMI_CON3,
> +				      RG_HDMITX_PRD_IMP_EN);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON4,
> +				  (0x6 << PRD_IBIAS_CLK_SHIFT) |
> +				  (0x6 << PRD_IBIAS_D2_SHIFT) |
> +				  (0x6 << PRD_IBIAS_D1_SHIFT) |
> +				  (0x6 << PRD_IBIAS_D0_SHIFT),
> +				  RG_HDMITX_PRD_IBIAS_CLK |
> +				  RG_HDMITX_PRD_IBIAS_D2 |
> +				  RG_HDMITX_PRD_IBIAS_D1 |
> +				  RG_HDMITX_PRD_IBIAS_D0);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON3,
> +				  (0xf << DRV_IMP_EN_SHIFT),
> +				  RG_HDMITX_DRV_IMP_EN);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON6,
> +				  (hdmi_phy->drv_imp_clk << DRV_IMP_CLK_SHIFT) |
> +				  (hdmi_phy->drv_imp_d2 << DRV_IMP_D2_SHIFT) |
> +				  (hdmi_phy->drv_imp_d1 << DRV_IMP_D1_SHIFT) |
> +				  (hdmi_phy->drv_imp_d0 << DRV_IMP_D0_SHIFT),
> +				  RG_HDMITX_DRV_IMP_CLK | RG_HDMITX_DRV_IMP_D2 |
> +				  RG_HDMITX_DRV_IMP_D1 | RG_HDMITX_DRV_IMP_D0);
> +		mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON5,
> +				  (hdmi_phy->ibias_up << DRV_IBIAS_CLK_SHIFT) |
> +				  (hdmi_phy->ibias_up << DRV_IBIAS_D2_SHIFT) |
> +				  (hdmi_phy->ibias_up << DRV_IBIAS_D1_SHIFT) |
> +				  (hdmi_phy->ibias_up << DRV_IBIAS_D0_SHIFT),
> +				  RG_HDMITX_DRV_IBIAS_CLK |
> +				  RG_HDMITX_DRV_IBIAS_D2 |
> +				  RG_HDMITX_DRV_IBIAS_D1 |
> +				  RG_HDMITX_DRV_IBIAS_D0);
> +	}

'if' part and 'else' part looks almost the same. Use variable for
difference and merge these two part. For example:

if (rate < 165000000)
	prd_ibias = 0x3;
else
	prd_ibias = 0x6;

mtk_hdmi_phy_mask(hdmi_phy, HDMI_CON4,
		  (prd_ibias << PRD_IBIAS_CLK_SHIFT) |
		  (prd_ibias << PRD_IBIAS_D2_SHIFT) |
		  (prd_ibias << PRD_IBIAS_D1_SHIFT) |
		  (prd_ibias << PRD_IBIAS_D0_SHIFT),
		  RG_HDMITX_PRD_IBIAS_CLK |
		  RG_HDMITX_PRD_IBIAS_D2 |
		  RG_HDMITX_PRD_IBIAS_D1 |
		  RG_HDMITX_PRD_IBIAS_D0);

>  	return 0;
>  }
>  

Regards,
CK

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