linux-kernel - Re: [RFC] clk: Remove cached cores in parent map during unregister

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Message-ID: <cda27c942f332d9da47fe8c4c5305207@codeaurora.org>
Date:   Wed, 21 Aug 2019 18:42:50 +0000
From:   saiprakash.ranjan@...eaurora.org
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, Rob Clark <robclark@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [RFC] clk: Remove cached cores in parent map during unregister

Hi Stephen,

On 2019-08-21 18:10, Stephen Boyd wrote:
> 
> Here's an attempt at the simple approach. There's another problem where
> the cached 'hw' member of the parent data is held around when we don't
> know when the caller has destroyed it. Not much else we can do for that
> though.
> 
> ---8<---
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index c0990703ce54..f42a803fb11a 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -3737,6 +3737,37 @@ static const struct clk_ops clk_nodrv_ops = {
>  	.set_parent	= clk_nodrv_set_parent,
>  };
> 
> +static void clk_core_evict_parent_cache_subtree(struct clk_core *root,
> +						struct clk_core *target)
> +{
> +	int i;
> +	struct clk_core *child;
> +
> +	if (!root)
> +		return;
> +
> +	for (i = 0; i < root->num_parents; i++)
> +		if (root->parents[i].core == target)
> +			root->parents[i].core = NULL;
> +
> +	hlist_for_each_entry(child, &root->children, child_node)
> +		clk_core_evict_parent_cache_subtree(child, target);
> +}
> +
> +/* Remove this clk from all parent caches */
> +static void clk_core_evict_parent_cache(struct clk_core *core)
> +{
> +	struct hlist_head **lists;
> +	struct clk_core *root;
> +
> +	lockdep_assert_held(&prepare_lock);
> +
> +	for (lists = all_lists; *lists; lists++)
> +		hlist_for_each_entry(root, *lists, child_node)
> +			clk_core_evict_parent_cache_subtree(root, core);
> +
> +}
> +
>  /**
>   * clk_unregister - unregister a currently registered clock
>   * @clk: clock to unregister
> @@ -3775,6 +3806,8 @@ void clk_unregister(struct clk *clk)
>  			clk_core_set_parent_nolock(child, NULL);
>  	}
> 
> +	clk_core_evict_parent_cache(clk->core);
> +
>  	hlist_del_init(&clk->core->child_node);
> 
>  	if (clk->core->prepare_count)


Thanks for the patch. This fixes the dispcc issue which I was observing 
with latest kernel on cheza.
You can have the tested by when you post the actual patch.

Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>

For reference, below is the error log:

[    3.992243] msm ae00000.mdss: Adding to iommu group 1
[    3.999877] msm ae00000.mdss: bound ae01000.mdp (ops 
0xffffff8010a87b78)
[    4.023597] msm ae00000.mdss: failed to bind ae94000.dsi (ops 
0xffffff8010a8b360): -517
[    4.031898] msm ae00000.mdss: master bind failed: -517
[    5.297509] msm ae00000.mdss: bound ae01000.mdp (ops 
0xffffff8010a87b78)
[    5.320906] msm ae00000.mdss: failed to bind ae94000.dsi (ops 
0xffffff8010a8b360): -517
[    5.329261] msm ae00000.mdss: master bind failed: -517
[    5.648667] msm ae00000.mdss: bound ae01000.mdp (ops 
0xffffff8010a87b78)
[    5.672005] clk_core_set_parent_nolock: clk dsi0_phy_pll_out_byteclk 
can not be parent of clk disp_cc_mdss_byte0_clk_src p_index=-22 <--- 
error
[    5.699799] msm ae00000.mdss: failed to bind ae94000.dsi (ops 
0xffffff8010a8b360): -22
[    5.708086] msm ae00000.mdss: master bind failed: -22
[    5.714052] msm: probe of ae00000.mdss failed with error -22

[    6.033541] clk_core_set_parent_nolock: clk dsi0_phy_pll_out_dsiclk 
can not be parent of clk disp_cc_mdss_pclk0_clk_src p_index=-22 <--- 
error

Thanks,
Sai

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