linux-kernel - Re: [PATCH v4 4/4] drm/msm/dsi/phy: Define PHY_CMN_CLK

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Message-ID: <waevglqatvykntxnmaahjpgbhipxhtcfpn7gfwud4sdidqh3dz@bfm7foignlm4>
Date: Mon, 17 Feb 2025 17:16:27 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Rob Clark <robdclark@...il.com>, 
	Abhinav Kumar <quic_abhinavk@...cinc.com>, Sean Paul <sean@...rly.run>, 
	Marijn Suijten <marijn.suijten@...ainline.org>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Jonathan Marek <jonathan@...ek.ca>, 
	linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org, Rob Clark <robdclark@...omium.org>
Subject: Re: [PATCH v4 4/4] drm/msm/dsi/phy: Define PHY_CMN_CLK_CFG[01]
 bitfields and simplify saving

On Mon, Feb 17, 2025 at 02:37:31PM +0100, Krzysztof Kozlowski wrote:
> On 17/02/2025 14:13, Dmitry Baryshkov wrote:
> > On Mon, Feb 17, 2025 at 12:53:17PM +0100, Krzysztof Kozlowski wrote:
> >> Add bitfields for PHY_CMN_CLK_CFG0 and PHY_CMN_CLK_CFG1 registers to
> >> avoid hard-coding bit masks and shifts and make the code a bit more
> >> readable.  While touching the lines in dsi_7nm_pll_save_state()
> >> resulting cached->pix_clk_div assignment would be too big, so just
> >> combine pix_clk_div and bit_clk_div into one cached state to make
> >> everything simpler.
> >>
> >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> >>
> >> ---
> >>
> >> Changes in v4:
> >> 1. Add mising bitfield.h include
> >> 2. One more FIELD_GET and DSI_7nm_PHY_CMN_CLK_CFG1_DSICLK_SEL (Dmitry)
> >>
> >> Changes in v3:
> >> 1. Use FIELD_GET
> >> 2. Keep separate bit_clk_div and pix_clk_div
> >> 3. Rebase (some things moved to previous patches)
> >>
> >> Changes in v2:
> >> 1. New patch
> >> ---
> >>  drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c             | 13 ++++++++-----
> >>  drivers/gpu/drm/msm/registers/display/dsi_phy_7nm.xml |  1 +
> >>  2 files changed, 9 insertions(+), 5 deletions(-)
> >>
> >> @@ -739,7 +741,8 @@ static int pll_7nm_register(struct dsi_pll_7nm *pll_7nm, struct clk_hw **provide
> >>  		u32 data;
> >>  
> >>  		data = readl(pll_7nm->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
> >> -		writel(data | 3, pll_7nm->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
> >> +		writel(data | DSI_7nm_PHY_CMN_CLK_CFG1_DSICLK_SEL(3),
> >> +		       pll_7nm->phy->base + REG_DSI_7nm_PHY_CMN_CLK_CFG1);
> > 
> > Nit: should this also be using dsi_pll_cmn_clk_cfg1_update() ?
> 
> 
> This is before clocks are registered so there is really no chance for
> simultaneous access.
> 
> It is rather then question of code readability or obviousness.

That's why I added it as a nit. I don't think that it's required, but I
think it might improve the patch.

-- 
With best wishes
Dmitry