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SubjectRe: [PATCH 2/9] clk: Introduce get_parent_hw clk op
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On 1/28/2019 11:10 PM, Stephen Boyd wrote:
> The clk_ops::get_parent function is limited in ability to return errors
> because it returns a u8. A "workaround" to return an error is to return
> a number >= the number of parents of a clk. This will in turn cause the
> framework to "orphan" the clk and make the parent of the clk NULL. This
> isn't really correct, because if an error occurs while reading the
> parents of a clk we should fail the clk registration, instead of
> orphaning the clk and waiting for the clk to appear later.
>
> We really need to have three different return values from the get_parent
> clk op. Something valid for a clk that exists, something invalid for a
> clk that doesn't exist and never will exist or can't be determined
> because the register operation to read the parent failed, and something
> for a clk that doesn't exist because the framework doesn't know about
> what it is. Introduce a new clk_op that can express all of this by
> returning a pointer to the clk_hw of the parent. It's expected that clk
> provider drivers will return a valid pointer when the parent is
> findable, an error pointer like EPROBE_DEFER if their parent provider
> hasn't probed yet but is valid, a NULL pointer if they can't find the
> clk but index is valid, and an error pointer with an appropriate error
> code otherwise.
>
> Cc: Miquel Raynal <miquel.raynal@bootlin.com>
> Cc: Jerome Brunet <jbrunet@baylibre.com>
> Cc: Russell King <linux@armlinux.org.uk>
> Cc: Michael Turquette <mturquette@baylibre.com>
> Signed-off-by: Stephen Boyd <sboyd@kernel.org>

<snip>

> +static int clk_init_parent(struct clk_core *core)
> +{
> + core->parent = __clk_init_parent(core, true);
> + if (IS_ERR(core->parent))
> + return PTR_ERR(core->parent);
> +
> + /*
> + * Populate core->parent if parent has already been clk_core_init'd. If
> + * parent has not yet been clk_core_init'd then place clk in the orphan
> + * list. If clk doesn't have any parents then place it in the root
> + * clk list.
> + *
> + * Every time a new clk is clk_init'd then we walk the list of orphan
> + * clocks and re-parent any that are children of the clock currently
> + * being clk_init'd.
> + */
> + if (core->parent) {
> + hlist_add_head(&core->child_node,
> + &core->parent->children);
> + core->orphan = core->parent->orphan;
> + } else if (!core->num_parents) {
> + hlist_add_head(&core->child_node, &clk_root_list);
> + core->orphan = false;
> + } else {
> + hlist_add_head(&core->child_node, &clk_orphan_list);

Missing "core->orphan = true;"?
The snippet below had that line. Its not clear why it appears to be
dropped here.

> + }
> +
> + return 0;
> +}

<snip>

> @@ -3073,29 +3143,9 @@ static int __clk_core_init(struct clk_core *core)
> "%s: invalid NULL in %s's .parent_names\n",
> __func__, core->name);
>
> - core->parent = __clk_init_parent(core);
> -
> - /*
> - * Populate core->parent if parent has already been clk_core_init'd. If
> - * parent has not yet been clk_core_init'd then place clk in the orphan
> - * list. If clk doesn't have any parents then place it in the root
> - * clk list.
> - *
> - * Every time a new clk is clk_init'd then we walk the list of orphan
> - * clocks and re-parent any that are children of the clock currently
> - * being clk_init'd.
> - */
> - if (core->parent) {
> - hlist_add_head(&core->child_node,
> - &core->parent->children);
> - core->orphan = core->parent->orphan;
> - } else if (!core->num_parents) {
> - hlist_add_head(&core->child_node, &clk_root_list);
> - core->orphan = false;
> - } else {
> - hlist_add_head(&core->child_node, &clk_orphan_list);
> - core->orphan = true;
> - }
> + ret = clk_init_parent(core);
> + if (ret)
> + goto out;
>
> /*
> * optional platform-specific magic


--
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.

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