| Message ID | 20221018-clk-range-checks-fixes-v3-0-9a1358472d52@cerno.tech (mailing list archive) |
|---|---|
| Headers | show |
| Series | clk: Make determine_rate mandatory for muxes | expand |
On 04/04/2023 11:11, Maxime Ripard wrote: > The Versatile sp810 "timerclken" clock implements a mux with a > set_parent hook, but doesn't provide a determine_rate implementation. > > This is a bit odd, since set_parent() is there to, as its name implies, > change the parent of a clock. Explanation of this mystery is pretty simple - the original patch: commit 6e973d2c438502dcf956e76305258ba7d1c7d1d3 Author: Pawel Moll <pawel.moll@arm.com> Date: Thu Apr 18 18:23:22 2013 +0100 clk: vexpress: Add separate SP810 driver predates introduction of determine_rate to clk_ops... commit 71472c0c06cf9a3d1540762ea205654c584e3bc4 Author: James Hogan <jhogan@kernel.org> Date: Mon Jul 29 12:25:00 2013 +0100 clk: add support for clock reparent on set_rate and clearly no one (the author included ;-) bothered to have another look at this side of the driver. > And if it was an oversight, then we are at least explicit about our > behavior now and it can be further refined down the line. It's been one hell of a memory lane trip, but my recollection suggest that the main goal of the driver was simply initialisation of the mux to select the 1MHz parent, because the other option - 32kHz - just didn't make any sense whatsoever. And that would be the case on every single platform using SP810 I know (or at least: knew), so it's seems to me that making the state permanent, as you're suggesting (or I think you're suggesting?) it's the right thing to do. Thanks! Paweł
Quoting Maxime Ripard (2023-04-04 03:10:50) > Hi, > > This is a follow-up to a previous series that was printing a warning > when a mux has a set_parent implementation but is missing > determine_rate(). > > The rationale is that set_parent() is very likely to be useful when > changing the rate, but it's determine_rate() that takes the parenting > decision. If we're missing it, then the current parent is always going > to be used, and thus set_parent() will not be used. The only exception > being a direct call to clk_set_parent(), but those are fairly rare > compared to clk_set_rate(). > > Stephen then asked to promote the warning to an error, and to fix up all > the muxes that are in that situation first. So here it is :) > Thanks for resending. I was thinking that we apply this patch first and then set determine_rate clk_ops without setting the clk flag. The function name is up for debate. ---8<--- diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 27c30a533759..057dd3ca8920 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -594,45 +594,57 @@ clk_core_forward_rate_req(struct clk_core *core, req->max_rate = old_req->max_rate; } -int clk_mux_determine_rate_flags(struct clk_hw *hw, - struct clk_rate_request *req, - unsigned long flags) +static int +clk_core_determine_rate_noreparent(struct clk_core *core, + struct clk_rate_request *req) { - struct clk_core *core = hw->core, *parent, *best_parent = NULL; - int i, num_parents, ret; + struct clk_core *parent; + int ret; unsigned long best = 0; - /* if NO_REPARENT flag set, pass through to current parent */ - if (core->flags & CLK_SET_RATE_NO_REPARENT) { - parent = core->parent; - if (core->flags & CLK_SET_RATE_PARENT) { - struct clk_rate_request parent_req; - - if (!parent) { - req->rate = 0; - return 0; - } + parent = core->parent; + if (core->flags & CLK_SET_RATE_PARENT) { + struct clk_rate_request parent_req; - clk_core_forward_rate_req(core, req, parent, &parent_req, req->rate); + if (!parent) { + req->rate = 0; + return 0; + } - trace_clk_rate_request_start(&parent_req); + clk_core_forward_rate_req(core, req, parent, &parent_req, req->rate); - ret = clk_core_round_rate_nolock(parent, &parent_req); - if (ret) - return ret; + trace_clk_rate_request_start(&parent_req); - trace_clk_rate_request_done(&parent_req); + ret = clk_core_round_rate_nolock(parent, &parent_req); + if (ret) + return ret; - best = parent_req.rate; - } else if (parent) { - best = clk_core_get_rate_nolock(parent); - } else { - best = clk_core_get_rate_nolock(core); - } + trace_clk_rate_request_done(&parent_req); - goto out; + best = parent_req.rate; + } else if (parent) { + best = clk_core_get_rate_nolock(parent); + } else { + best = clk_core_get_rate_nolock(core); } + req->rate = best; + + return 0; +} + +int clk_mux_determine_rate_flags(struct clk_hw *hw, + struct clk_rate_request *req, + unsigned long flags) +{ + struct clk_core *core = hw->core, *parent, *best_parent = NULL; + int i, num_parents, ret; + unsigned long best = 0; + + /* if NO_REPARENT flag set, pass through to current parent */ + if (core->flags & CLK_SET_RATE_NO_REPARENT) + return clk_core_determine_rate_noreparent(core, req); + /* find the parent that can provide the fastest rate <= rate */ num_parents = core->num_parents; for (i = 0; i < num_parents; i++) { @@ -670,9 +682,7 @@ int clk_mux_determine_rate_flags(struct clk_hw *hw, if (!best_parent) return -EINVAL; -out: - if (best_parent) - req->best_parent_hw = best_parent->hw; + req->best_parent_hw = best_parent->hw; req->best_parent_rate = best; req->rate = best; @@ -772,6 +782,24 @@ int __clk_mux_determine_rate_closest(struct clk_hw *hw, } EXPORT_SYMBOL_GPL(__clk_mux_determine_rate_closest); +/** + * clk_hw_determine_rate_noreparent - clk_ops::determine_rate implementation for a clk that doesn't reparent + * @hw: clk to determine rate on + * @req: rate request + * + * Helper for finding best parent rate to provide a given frequency. This can + * be used directly as a determine_rate callback (e.g. for a mux), or from a + * more complex clock that may combine a mux with other operations. + * + * Returns: 0 on success, -EERROR value on error + */ +int clk_hw_determine_rate_noreparent(struct clk_hw *hw, + struct clk_rate_request *req) +{ + return clk_core_determine_rate_noreparent(hw->core, req); +} +EXPORT_SYMBOL_GPL(clk_hw_determine_rate_noreparent); + /*** clk api ***/ static void clk_core_rate_unprotect(struct clk_core *core) diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h index 28ff6f1a6ada..958977231ff7 100644 --- a/include/linux/clk-provider.h +++ b/include/linux/clk-provider.h @@ -1333,6 +1333,8 @@ int __clk_mux_determine_rate_closest(struct clk_hw *hw, int clk_mux_determine_rate_flags(struct clk_hw *hw, struct clk_rate_request *req, unsigned long flags); +int clk_hw_determine_rate_noreparent(struct clk_hw *hw, + struct clk_rate_request *req); void clk_hw_reparent(struct clk_hw *hw, struct clk_hw *new_parent); void clk_hw_get_rate_range(struct clk_hw *hw, unsigned long *min_rate, unsigned long *max_rate);
On Thu, Apr 13, 2023 at 02:44:51PM -0700, Stephen Boyd wrote: > Quoting Maxime Ripard (2023-04-04 03:10:50) > > Hi, > > > > This is a follow-up to a previous series that was printing a warning > > when a mux has a set_parent implementation but is missing > > determine_rate(). > > > > The rationale is that set_parent() is very likely to be useful when > > changing the rate, but it's determine_rate() that takes the parenting > > decision. If we're missing it, then the current parent is always going > > to be used, and thus set_parent() will not be used. The only exception > > being a direct call to clk_set_parent(), but those are fairly rare > > compared to clk_set_rate(). > > > > Stephen then asked to promote the warning to an error, and to fix up all > > the muxes that are in that situation first. So here it is :) > > > > Thanks for resending. > > I was thinking that we apply this patch first and then set > determine_rate clk_ops without setting the clk flag. The function name > is up for debate. Ack, I'll send a new version following your proposal Maxime
Hi, This is a follow-up to a previous series that was printing a warning when a mux has a set_parent implementation but is missing determine_rate(). The rationale is that set_parent() is very likely to be useful when changing the rate, but it's determine_rate() that takes the parenting decision. If we're missing it, then the current parent is always going to be used, and thus set_parent() will not be used. The only exception being a direct call to clk_set_parent(), but those are fairly rare compared to clk_set_rate(). Stephen then asked to promote the warning to an error, and to fix up all the muxes that are in that situation first. So here it is :) It was build-tested on x86, arm and arm64. Affected drivers have been tracked down by the following coccinelle script: virtual report @ clk_ops @ identifier ops; position p; @@ struct clk_ops ops@p = { ... }; @ has_set_parent @ identifier clk_ops.ops; identifier set_parent_f; @@ struct clk_ops ops = { .set_parent = set_parent_f, }; @ has_determine_rate @ identifier clk_ops.ops; identifier determine_rate_f; @@ struct clk_ops ops = { .determine_rate = determine_rate_f, }; @ script:python depends on report && has_set_parent && !has_determine_rate @ ops << clk_ops.ops; set_parent_f << has_set_parent.set_parent_f; p << clk_ops.p; @@ coccilib.report.print_report(p[0], "ERROR: %s has set_parent (%s)" % (ops, set_parent_f)) Berlin is the only user still matching after this series has been applied, but it's because it uses a composite clock which throws the script off. The driver has been converted and shouldn't be a problem. Let me know what you think, Maxime Signed-off-by: Maxime Ripard <maxime@cerno.tech> --- Changes in v3: - Rebased on top of next-20230404 - Link to v2: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v2-0-f6736dec138e@cerno.tech Changes in v2: - Drop all the patches already applied - Promote the clk registration warning to an error - Make all muxes use determine_rate - Link to v1: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v1-0-f3ef80518140@cerno.tech --- Maxime Ripard (65): clk: Export clk_hw_forward_rate_request() clk: lan966x: Remove unused round_rate hook clk: nodrv: Add a determine_rate hook clk: test: Add a determine_rate hook clk: actions: composite: Add a determine_rate hook for pass clk clk: at91: main: Add a determine_rate hook clk: at91: sckc: Add a determine_rate hook clk: berlin: div: Add a determine_rate hook clk: cdce706: Add a determine_rate hook clk: k210: pll: Add a determine_rate hook clk: k210: aclk: Add a determine_rate hook clk: k210: mux: Add a determine_rate hook clk: lmk04832: clkout: Add a determine_rate hook clk: lochnagar: Add a determine_rate hook clk: qoriq: Add a determine_rate hook clk: si5341: Add a determine_rate hook clk: stm32f4: mux: Add a determine_rate hook clk: vc5: mux: Add a determine_rate hook clk: vc5: clkout: Add a determine_rate hook clk: wm831x: clkout: Add a determine_rate hook clk: davinci: da8xx-cfgchip: Add a determine_rate hook clk: davinci: da8xx-cfgchip: Add a determine_rate hook clk: imx: busy: Add a determine_rate hook clk: imx: fixup-mux: Add a determine_rate hook clk: imx: scu: Add a determine_rate hook clk: mediatek: cpumux: Add a determine_rate hook clk: pxa: Add a determine_rate hook clk: renesas: r9a06g032: Add a determine_rate hook clk: socfpga: gate: Add a determine_rate hook clk: stm32: core: Add a determine_rate hook clk: tegra: bpmp: Add a determine_rate hook clk: tegra: super: Add a determine_rate hook clk: tegra: periph: Add a determine_rate hook clk: ux500: prcmu: Add a determine_rate hook clk: ux500: sysctrl: Add a determine_rate hook clk: versatile: sp810: Add a determine_rate hook drm/tegra: sor: Add a determine_rate hook phy: cadence: sierra: Add a determine_rate hook phy: cadence: torrent: Add a determine_rate hook phy: ti: am654-serdes: Add a determine_rate hook phy: ti: j721e-wiz: Add a determine_rate hook rtc: sun6i: Add a determine_rate hook ASoC: tlv320aic32x4: Add a determine_rate hook clk: actions: composite: div: Switch to determine_rate clk: actions: composite: fact: Switch to determine_rate clk: at91: smd: Switch to determine_rate clk: axi-clkgen: Switch to determine_rate clk: cdce706: divider: Switch to determine_rate clk: cdce706: clkout: Switch to determine_rate clk: si5341: Switch to determine_rate clk: si5351: pll: Switch to determine_rate clk: si5351: msynth: Switch to determine_rate clk: si5351: clkout: Switch to determine_rate clk: da8xx: clk48: Switch to determine_rate clk: imx: scu: Switch to determine_rate clk: ingenic: cgu: Switch to determine_rate clk: ingenic: tcu: Switch to determine_rate clk: sprd: composite: Switch to determine_rate clk: st: flexgen: Switch to determine_rate clk: stm32: composite: Switch to determine_rate clk: tegra: periph: Switch to determine_rate clk: tegra: super: Switch to determine_rate ASoC: tlv320aic32x4: pll: Switch to determine_rate ASoC: tlv320aic32x4: div: Switch to determine_rate clk: Forbid to register a mux without determine_rate drivers/clk/actions/owl-composite.c | 35 +++++++++++----- drivers/clk/actions/owl-composite.h | 2 +- drivers/clk/at91/clk-main.c | 3 +- drivers/clk/at91/clk-smd.c | 29 +++++++------ drivers/clk/at91/sckc.c | 3 +- drivers/clk/berlin/berlin2-div.c | 3 +- drivers/clk/clk-axi-clkgen.c | 14 ++++--- drivers/clk/clk-cdce706.c | 31 ++++++++------ drivers/clk/clk-k210.c | 17 +++++--- drivers/clk/clk-lan966x.c | 17 -------- drivers/clk/clk-lmk04832.c | 1 + drivers/clk/clk-lochnagar.c | 2 + drivers/clk/clk-qoriq.c | 10 +++-- drivers/clk/clk-si5341.c | 21 +++++----- drivers/clk/clk-si5351.c | 67 +++++++++++++++++-------------- drivers/clk/clk-stm32f4.c | 3 +- drivers/clk/clk-versaclock5.c | 8 ++-- drivers/clk/clk-wm831x.c | 3 +- drivers/clk/clk.c | 15 +++++++ drivers/clk/clk_test.c | 1 + drivers/clk/davinci/da8xx-cfgchip.c | 15 ++++--- drivers/clk/imx/clk-busy.c | 3 +- drivers/clk/imx/clk-fixup-mux.c | 3 +- drivers/clk/imx/clk-scu.c | 27 +++++++++++-- drivers/clk/ingenic/cgu.c | 15 +++---- drivers/clk/ingenic/tcu.c | 19 +++++---- drivers/clk/mediatek/clk-cpumux.c | 3 +- drivers/clk/pxa/clk-pxa.c | 3 +- drivers/clk/renesas/r9a06g032-clocks.c | 3 +- drivers/clk/socfpga/clk-gate.c | 3 +- drivers/clk/sprd/composite.c | 16 +++++--- drivers/clk/st/clk-flexgen.c | 15 +++---- drivers/clk/stm32/clk-stm32-core.c | 33 ++++++++++----- drivers/clk/tegra/clk-bpmp.c | 7 +++- drivers/clk/tegra/clk-periph.c | 19 ++++++--- drivers/clk/tegra/clk-super.c | 18 ++++++--- drivers/clk/ux500/clk-prcmu.c | 3 +- drivers/clk/ux500/clk-sysctrl.c | 4 +- drivers/clk/versatile/clk-sp810.c | 3 +- drivers/gpu/drm/tegra/sor.c | 3 +- drivers/phy/cadence/phy-cadence-sierra.c | 1 + drivers/phy/cadence/phy-cadence-torrent.c | 1 + drivers/phy/ti/phy-am654-serdes.c | 1 + drivers/phy/ti/phy-j721e-wiz.c | 1 + drivers/rtc/rtc-sun6i.c | 2 + sound/soc/codecs/tlv320aic32x4-clk.c | 37 ++++++++++------- 46 files changed, 343 insertions(+), 200 deletions(-) --- base-commit: 6a53bda3aaf3de5edeea27d0b1d8781d067640b6 change-id: 20221018-clk-range-checks-fixes-2039f3523240 Best regards,