linux-kernel - Re: [PATCH v3 2/4] drm/msm/dsi/phy: Protect PHY_CMN_CLK

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Message-ID: <c39b8879-0a43-4a54-8084-d11ca3ede518@quicinc.com>
Date: Sat, 15 Feb 2025 09:39:05 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Rob Clark
	<robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        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>
CC: <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 v3 2/4] drm/msm/dsi/phy: Protect PHY_CMN_CLK_CFG1 against
 clock driver



On 2/14/2025 7:08 AM, Krzysztof Kozlowski wrote:
> PHY_CMN_CLK_CFG1 register is updated by the PHY driver and by a mux
> clock from Common Clock Framework:
> devm_clk_hw_register_mux_parent_hws().  There could be a path leading to
> concurrent and conflicting updates between PHY driver and clock
> framework, e.g. changing the mux and enabling PLL clocks.
> 
> Add dedicated spinlock to be sure all PHY_CMN_CLK_CFG1 updates are
> synchronized.
> 
> While shuffling the code, define and use PHY_CMN_CLK_CFG1 bitfields to
> make the code more readable and obvious.
> 
> Fixes: 1ef7c99d145c ("drm/msm/dsi: add support for 7nm DSI PHY/PLL")
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> 
> ---
> 
> Changes in v3:
> 1. Define bitfields (move here parts from patch #4)
> 
> Changes in v2:
> 1. Store BIT(4) and BIT(5) in local var in dsi_pll_enable_global_clk()
> ---
>   drivers/gpu/drm/msm/dsi/phy/dsi_phy_7nm.c          | 35 ++++++++++++++--------
>   .../gpu/drm/msm/registers/display/dsi_phy_7nm.xml  |  5 +++-
>   2 files changed, 26 insertions(+), 14 deletions(-)
> 

Reviewed-by: Abhinav Kumar <quic_abhinavk@...cinc.com>