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Sat, 15 Feb 2025 05:55:53 -0800 (PST) Message-ID: Date: Sat, 15 Feb 2025 15:55:51 +0200 Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 9/9] clk: Overwrite clk_hw::init with NULL during clk_register() To: Stephen Boyd , Michael Turquette Cc: linux-kernel@vger.kernel.org, linux-clk@vger.kernel.org, Bjorn Andersson , Doug Anderson References: <20190731193517.237136-1-sboyd@kernel.org> <20190731193517.237136-10-sboyd@kernel.org> From: Claudiu Beznea Content-Language: en-US In-Reply-To: <20190731193517.237136-10-sboyd@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, Stephen, On 31.07.2019 22:35, Stephen Boyd wrote: > We don't want clk provider drivers to use the init structure after clk > registration time, but we leave a dangling reference to it by means of > clk_hw::init. Let's overwrite the member with NULL during clk_register() > so that this can't be used anymore after registration time. > > Cc: Bjorn Andersson > Cc: Doug Anderson > Signed-off-by: Stephen Boyd > --- > > Please ack so I can take this through clk tree > > drivers/clk/clk.c | 24 ++++++++++++++++-------- > include/linux/clk-provider.h | 3 ++- > 2 files changed, 18 insertions(+), 9 deletions(-) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index c0990703ce54..efac620264a2 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -3484,9 +3484,9 @@ static int clk_cpy_name(const char **dst_p, const char *src, bool must_exist) > return 0; > } > > -static int clk_core_populate_parent_map(struct clk_core *core) > +static int clk_core_populate_parent_map(struct clk_core *core, > + const struct clk_init_data *init) > { > - const struct clk_init_data *init = core->hw->init; > u8 num_parents = init->num_parents; > const char * const *parent_names = init->parent_names; > const struct clk_hw **parent_hws = init->parent_hws; > @@ -3566,6 +3566,14 @@ __clk_register(struct device *dev, struct device_node *np, struct clk_hw *hw) > { > int ret; > struct clk_core *core; > + const struct clk_init_data *init = hw->init; > + > + /* > + * The init data is not supposed to be used outside of registration path. > + * Set it to NULL so that provider drivers can't use it either and so that > + * we catch use of hw->init early on in the core. > + */ > + hw->init = NULL; I found that this line impact the drivers/clk/clk-versaclock3.c driver when doing unbind/bind. The driver provides statically initialized hw.init object for registration, the hw.init pointers are set to NULL after clock registrations then the next registration (when re-binding) fails. In the driver probe the clock are registered like: for (i = 0; i < ARRAY_SIZE(clk_pfd_mux); i++) { clk_pfd_mux[i].regmap = regmap; ret = devm_clk_hw_register(dev, &clk_pfd_mux[i].hw); if (ret) return dev_err_probe(dev, ret, "%s failed\n", clk_pfd_mux[i].hw.init->name); } and entries in clk_pfd_mux[] are like: static struct vc3_hw_data clk_pfd_mux[] = { [VC3_PFD2_MUX] = { .data = &(struct vc3_clk_data) { .offs = VC3_PLL_OP_CTRL, .bitmsk = BIT(VC3_PLL_OP_CTRL_PLL2_REFIN_SEL) }, .hw.init = &(struct clk_init_data) { .name = "pfd2_mux", .ops = &vc3_pfd_mux_ops, .parent_data = pfd_mux_parent_data, .num_parents = 2, .flags = CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT } }, // ... }; I tried with the following diff, too: diff --git a/drivers/clk/clk-versaclock3.c b/drivers/clk/clk-versaclock3.c index 9fe27dace111..c1776c313e9b 100644 --- a/drivers/clk/clk-versaclock3.c +++ b/drivers/clk/clk-versaclock3.c @@ -1022,10 +1022,11 @@ static int vc3_probe(struct i2c_client *client) /* Register pfd muxes */ for (i = 0; i < ARRAY_SIZE(clk_pfd_mux); i++) { clk_pfd_mux[i].regmap = regmap; + pr_err("%s(): hw init=%08x\n", __func__, clk_pfd_mux[i].hw.init); ret = devm_clk_hw_register(dev, &clk_pfd_mux[i].hw); if (ret) return dev_err_probe(dev, ret, "%s failed\n", - clk_pfd_mux[i].hw.init->name); + "test"); //clk_pfd_mux[i].hw.init->name); } /* Register pfd's */ @@ -1034,7 +1035,7 @@ static int vc3_probe(struct i2c_client *client) ret = devm_clk_hw_register(dev, &clk_pfd[i].hw); if (ret) return dev_err_probe(dev, ret, "%s failed\n", - clk_pfd[i].hw.init->name); + "test"); //clk_pfd[i].hw.init->name); } data = i2c_get_match_data(client); @@ -1050,7 +1051,7 @@ static int vc3_probe(struct i2c_client *client) ret = devm_clk_hw_register(dev, &clk_pll[i].hw); if (ret) return dev_err_probe(dev, ret, "%s failed\n", - clk_pll[i].hw.init->name); + "test"); //clk_pll[i].hw.init->name); } /* Register divider muxes */ @@ -1059,7 +1060,7 @@ static int vc3_probe(struct i2c_client *client) ret = devm_clk_hw_register(dev, &clk_div_mux[i].hw); if (ret) return dev_err_probe(dev, ret, "%s failed\n", - clk_div_mux[i].hw.init->name); + "test");//clk_div_mux[i].hw.init->name); } /* Register dividers */ @@ -1068,7 +1069,7 @@ static int vc3_probe(struct i2c_client *client) ret = devm_clk_hw_register(dev, &clk_div[i].hw); if (ret) return dev_err_probe(dev, ret, "%s failed\n", - clk_div[i].hw.init->name); + "test"); //clk_div[i].hw.init->name); } /* Register clk muxes */ @@ -1082,7 +1083,7 @@ static int vc3_probe(struct i2c_client *client) ret = devm_clk_hw_register(dev, &clk_mux[i].hw); if (ret) return dev_err_probe(dev, ret, "%s failed\n", - clk_mux[i].hw.init->name); + "test");//clk_mux[i].hw.init->name); } /* Register clk outputs */ Can you please let me know if this is a wrong pattern? I noticed there are other drivers following similar approach, e.g.: - drivers/clk/clk-axm5516.c - drivers/clk/qcom/camcc-sm6350.c - drivers/clk/meson/c3-pll.c Full console log with my trials can be found here: https://p.fr33tux.org/9d976f Thank you, Claudiu