linux-kernel - Re: [PATCH v5 16/24] drm/msm/dsi/phy: Fix reading zero as PLL rates when unprepared

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Message-ID: <da229728-300c-417f-bb21-426cfa6d2cd0@linaro.org>
Date: Wed, 30 Apr 2025 15:11:29 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: 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>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Krishna Manikandan <quic_mkrishn@...cinc.com>,
 Jonathan Marek <jonathan@...ek.ca>, Kuogee Hsieh <quic_khsieh@...cinc.com>,
 Neil Armstrong <neil.armstrong@...aro.org>,
 Dmitry Baryshkov <lumag@...nel.org>, Rob Clark <robdclark@...il.com>,
 Bjorn Andersson <andersson@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, Rob Clark <robdclark@...omium.org>,
 linux-clk@...r.kernel.org, Srinivas Kandagatla <srini@...nel.org>
Subject: Re: [PATCH v5 16/24] drm/msm/dsi/phy: Fix reading zero as PLL rates
 when unprepared

On 30/04/2025 15:00, Krzysztof Kozlowski wrote:
>  
> @@ -361,21 +373,46 @@ static int dsi_pll_7nm_lock_status(struct dsi_pll_7nm *pll)
>  
>  static void dsi_pll_disable_pll_bias(struct dsi_pll_7nm *pll)
>  {
> -	u32 data = readl(pll->phy->base + REG_DSI_7nm_PHY_CMN_CTRL_0);
> +	unsigned long flags;
> +	u32 data;
> +
> +	spin_lock_irqsave(&pll->pll_enable_lock, flags);
> +	--pll->pll_enable_cnt;
> +	if (pll->pll_enable_cnt < 0) {

I removed too much from debugging - this should be WARN_ON or dev_err


> +		spin_unlock_irqrestore(&pll->pll_enable_lock, flags);
> +		return;
> +	} else if (pll->pll_enable_cnt > 0) {
> +		spin_unlock_irqrestore(&pll->pll_enable_lock, flags);
> +		return;
> +	} /* else: == 0 */


Best regards,
Krzysztof