Messages in this thread | | | Subject | Re: [PATCH 01/21] opp: Manage empty OPP tables with clk handle | From | Rajendra Nayak <> | Date | Mon, 13 Apr 2020 16:04:02 +0530 |
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On 4/9/2020 1:27 PM, Viresh Kumar wrote: > On 08-04-20, 19:16, Rajendra Nayak wrote: >> With OPP core now supporting DVFS for IO devices, we have instances of >> IO devices (same IP block) which require an OPP on some platforms/SoCs > > By OPP you mean both freq and voltage here ?
yes, freq and perf state.
> >> while just needing to scale the clock on some others. > > And only freq here ?
yes.
> >> In order to avoid conditional code in every driver which supports such >> devices (to check for availability of OPPs and then deciding to do >> either dev_pm_opp_set_rate() or clk_set_rate()) add support to manage >> empty OPP tables with a clk handle. > > Why can't these devices have an opp table with just rate mentioned in each node > ?
These are existing devices already upstream.
> >> This makes dev_pm_opp_set_rate() equivalent of a clk_set_rate() for >> devices with just a clk and no OPPs specified, and makes >> dev_pm_opp_set_rate(0) bail out without throwing an error. >> >> Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org> >> --- >> drivers/opp/core.c | 14 ++++++++++++++ >> 1 file changed, 14 insertions(+) >> >> diff --git a/drivers/opp/core.c b/drivers/opp/core.c >> index ba43e6a..e4f01e7 100644 >> --- a/drivers/opp/core.c >> +++ b/drivers/opp/core.c >> @@ -819,6 +819,8 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) >> if (unlikely(!target_freq)) { >> if (opp_table->required_opp_tables) { >> ret = _set_required_opps(dev, opp_table, NULL); >> + } else if (!_get_opp_count(opp_table)) { >> + return 0; > > Why should anyone call this with target_freq = 0 ? I know it was required to > drop votes in the above case, but why here ?
Well, it is to drop votes. But in cases where we don't have perf votes being put (and only clock is scaled), the driver would still call this with freq = 0, i am just making sure that in such cases its treated as a nop.
> >> } else { >> dev_err(dev, "target frequency can't be 0\n"); >> ret = -EINVAL; >> @@ -849,6 +851,18 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq) >> goto put_opp_table; >> } >> >> + /* >> + * For IO devices which require an OPP on some platforms/SoCs >> + * while just needing to scale the clock on some others >> + * we look for empty OPP tables with just a clock handle and >> + * scale only the clk. This makes dev_pm_opp_set_rate() >> + * equivalent to a clk_set_rate() >> + */ >> + if (!_get_opp_count(opp_table)) { >> + ret = _generic_set_opp_clk_only(dev, clk, freq); >> + goto put_opp_table; >> + } >> + > > Is this enough? _of_add_opp_table_v2() returns with error if there is no OPP > node within the table. Please give an example of how DT looks for the case you > want to support.
FWIK, no one should call a _of_add_opp_table_v2 in cases where there is no OPP in DT? The 'empty' OPP table from what I understand will be created by dev_pm_opp_set_clkname. A good case to look at is the PATCH 13/21 in this series. The driver I am modifying is used on sdm845/sc7180 and a host of other older qualcomm SoCs. Since i am adding support for perf state voting using OPP only on sdm845/sc7180 I want the existing platforms to just do what they were doing. Now thats not possible unless I start adding a bunch of if/else around every opp call in the driver to distinguish between the two.
I am a little surprised since I though the idea of doing something like this came from you :) (or perhaps Stephen, I somehow can't recollect) to avoid all the if/else conditions I had when I initially posted some of these changes. Btw, you had this patch reviewed when this was posted a long while back too [1]
[1] https://patchwork.kernel.org/patch/11027217/
> >> temp_freq = old_freq; >> old_opp = _find_freq_ceil(opp_table, &temp_freq); >> if (IS_ERR(old_opp)) { >> -- >> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member >> of Code Aurora Forum, hosted by The Linux Foundation >
-- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
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