Messages in this thread Patch in this message | | | From | Stephen Boyd <> | Subject | Re: [PATCH v2 6/8] clk: Allow parents to be specified without string names | Date | Wed, 06 Mar 2019 09:48:52 -0800 |
| |
Quoting Jeffrey Hugo (2019-03-02 13:25:06) > On 2/26/2019 3:34 PM, Stephen Boyd wrote: > > The common clk framework is lacking in ability to describe the clk > > topology without specifying strings for every possible parent-child > > link. There are a few drawbacks to the current approach: > > > > 1) String comparisons are used for everything, including describing > > topologies that are 'local' to a single clock controller. > > > > 2) clk providers (e.g. i2c clk drivers) need to create globally unique > > clk names to avoid collisions in the clk namespace, leading to awkward > > name generation code in various clk drivers. > > > > 3) DT bindings may not fully describe the clk topology and linkages > > between clk controllers because drivers can easily rely on globally unique > > strings to describe connections between clks. > > > > This leads to confusing DT bindings, complicated clk name generation > > code, and inefficient string comparisons during clk registration just so > > that the clk framework can detect the topology of the clk tree. > > Furthermore, some drivers call clk_get() and then __clk_get_name() to > > extract the globally unique clk name just so they can specify the parent > > of the clk they're registering. We have of_clk_parent_fill() but that > > mostly only works for single clks registered from a DT node, which isn't > > the norm. Let's simplify this all by introducing two new ways of > > specifying clk parents. > > > > The first method is an array of pointers to clk_hw structures > > corresponding to the parents at that index. This works for clks that are > > registered when we have access to all the clk_hw pointers for the > > parents. > > > > The second method is a mix of clk_hw pointers and strings of local and > > global parent clk names. If the .name member of the map is set we'll > > look for that clk by performing a DT based lookup of the device the clk > > is registered with and the .name specified in the map. If that fails, > > we'll fallback to the .fallback member and perform a global clk name > > lookup like we've always done before. > > > > Using either one of these new methods is entirely optional. Existing > > drivers will continue to work, and they can migrate to this new approach > > as they see fit. Eventually, we'll want to get rid of the 'parent_names' > > array in struct clk_init_data and use one of these new methods instead. > > > > I don't know exactly what regressed from V1, but this change breaks all > clock drivers as far as I can tell. All clocks from old and new (ie > 8998 mmcc rebased onto this) drivers end up as orphans. > > Is there some data I can provide to help you figure out the issue? >
Can you try this patch? It fixes a pointer blunder that I'm sad about.
----8<----- diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 37aea7884166..d12afd256dc5 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -3297,15 +3297,17 @@ struct clk *clk_hw_create_clk(struct device *dev, struct clk_hw *hw, return clk; } -static int clk_cpy_name(const char *dst, const char *src, bool must_exist) +static int clk_cpy_name(const char **dst_p, const char *src, bool must_exist) { + const char *dst; + if (!src) { if (must_exist) return -EINVAL; return 0; } - dst = kstrdup_const(src, GFP_KERNEL); + *dst_p = dst = kstrdup_const(src, GFP_KERNEL); if (!dst) return -ENOMEM; @@ -3341,14 +3343,14 @@ static int clk_core_populate_parent_map(struct clk_core *core) WARN(!parent_names[i], "%s: invalid NULL in %s's .parent_names\n", __func__, core->name); - ret = clk_cpy_name(parent->name, parent_names[i], + ret = clk_cpy_name(&parent->name, parent_names[i], true); } else if (parent_data) { parent->hw = parent_data[i].hw; - ret = clk_cpy_name(parent->fw_name, + ret = clk_cpy_name(&parent->fw_name, parent_data[i].fw_name, false); if (!ret) - ret = clk_cpy_name(parent->name, + ret = clk_cpy_name(&parent->name, parent_data[i].name, false); } else if (parent_hws) {
| |