linux-kernel - Re: [PATCH] clk: sunxi-ng: common: Don't call hw_to_ccu

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Date: Thu, 27 Jun 2024 12:39:26 +0100
From: Måns Rullgård <mans@...sr.com>
To: Frank Oltmanns <frank@...manns.dev>
Cc: Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Chen-Yu Tsai <wens@...e.org>, Jernej Skrabec
 <jernej.skrabec@...il.com>, Samuel Holland <samuel@...lland.org>, Maxime
 Ripard <mripard@...nel.org>, linux-clk@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
 linux-kernel@...r.kernel.org, "Robert J. Pafford"
 <pafford.9@...keyemail.osu.edu>, stable@...r.kernel.org
Subject: Re: [PATCH] clk: sunxi-ng: common: Don't call hw_to_ccu_common on
 hw without common

Frank Oltmanns <frank@...manns.dev> writes:

> In order to set the rate range of a hw sunxi_ccu_probe calls
> hw_to_ccu_common() assuming all entries in desc->ccu_clks are contained
> in a ccu_common struct. This assumption is incorrect and, in
> consequence, causes invalid pointer de-references.
>
> Remove the faulty call. Instead, add one more loop that iterates over
> the ccu_clks and sets the rate range, if required.
>
> Fixes: b914ec33b391 ("clk: sunxi-ng: common: Support minimum and maximum rate")
> Reported-by: Robert J. Pafford <pafford.9@...keyemail.osu.edu>
> Closes: https://lore.kernel.org/lkml/DM6PR01MB58047C810DDD5D0AE397CADFF7C22@DM6PR01MB5804.prod.exchangelabs.com/
> Cc: stable@...r.kernel.org
> Signed-off-by: Frank Oltmanns <frank@...manns.dev>
> ---
> Robert, could you please test if this fixes the issue you reported.
>
> I'm CC'ing Måns here, because he observed some strange behavior [1] with
> the original patch. Is it possible for you to look into if this patch
> fixes your issue without the need for the following (seemingly
> unrelated) patches:
>       cedb7dd193f6 "drm/sun4i: hdmi: Convert encoder to atomic"
>       9ca6bc246035 "drm/sun4i: hdmi: Move mode_set into enable"

This does indeed fix it.  6.9 is still broken, though, but that's
probably for other reasons.

> Thanks,
>   Frank
>
> [1]: https://lore.kernel.org/lkml/yw1xo78z8ez0.fsf@mansr.com/
> ---
>  drivers/clk/sunxi-ng/ccu_common.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/clk/sunxi-ng/ccu_common.c b/drivers/clk/sunxi-ng/ccu_common.c
> index ac0091b4ce24..be375ce0149c 100644
> --- a/drivers/clk/sunxi-ng/ccu_common.c
> +++ b/drivers/clk/sunxi-ng/ccu_common.c
> @@ -132,7 +132,6 @@ static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
>
>  	for (i = 0; i < desc->hw_clks->num ; i++) {
>  		struct clk_hw *hw = desc->hw_clks->hws[i];
> -		struct ccu_common *common = hw_to_ccu_common(hw);
>  		const char *name;
>
>  		if (!hw)
> @@ -147,14 +146,21 @@ static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
>  			pr_err("Couldn't register clock %d - %s\n", i, name);
>  			goto err_clk_unreg;
>  		}
> +	}
> +
> +	for (i = 0; i < desc->num_ccu_clks; i++) {
> +		struct ccu_common *cclk = desc->ccu_clks[i];
> +
> +		if (!cclk)
> +			continue;
>
> -		if (common->max_rate)
> -			clk_hw_set_rate_range(hw, common->min_rate,
> -					      common->max_rate);
> +		if (cclk->max_rate)
> +			clk_hw_set_rate_range(&cclk->hw, cclk->min_rate,
> +					      cclk->max_rate);
>  		else
> -			WARN(common->min_rate,
> +			WARN(cclk->min_rate,
>  			     "No max_rate, ignoring min_rate of clock %d - %s\n",
> -			     i, name);
> +			     i, clk_hw_get_name(&cclk->hw));
>  	}
>
>  	ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
>
> ---
> base-commit: 2607133196c35f31892ee199ce7ffa717bea4ad1
> change-id: 20240622-sunxi-ng_fix_common_probe-5677c3e487fc
>
> Best regards,
> -- 
>
> Frank Oltmanns <frank@...manns.dev>
>

-- 
Måns Rullgård