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Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver

From Arnd Bergmann <arnd@arndb.de>
Newsgroups linux.kernel
Subject Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver
Date 2016-11-08 12:50 +0100
Message-ID <sBd4B-lV-3@gated-at.bofh.it> (permalink)
References <sz5Xz-87s-3@gated-at.bofh.it> <sB8HE-6cp-9@gated-at.bofh.it> <sB9aF-6lM-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Tuesday, November 8, 2016 1:08:31 PM CET Anurup M wrote:
 
> On Tuesday 08 November 2016 12:32 PM, Tan Xiaojun wrote:
> > On 2016/11/7 21:26, Arnd Bergmann wrote:
> >> On Wednesday, November 2, 2016 11:42:46 AM CET Anurup M wrote:
> >>> From: Tan Xiaojun <tanxiaojun@huawei.com>
> >>> +	/* ensure the djtag operation is done */
> >>> +	do {
> >>> +		djtag_read32_relaxed(regs_base, SC_DJTAG_MSTR_START_EN_EX, &rd);
> >>> +
> >>> +		if (!(rd & DJTAG_MSTR_START_EN_EX))
> >>> +			break;
> >>> +
> >>> +		udelay(1);
> >>> +	} while (timeout--);
> >> This one is obviously not performance critical at all, so use a non-relaxed
> >> accessor. Same for the other two in this function.
> >>
> >> Are these functions ever called from atomic context? If yes, please document
> >> from what context they can be called, otherwise please consider changing
> >> the udelay calls into sleeping waits.
> >>
> > Yes, this is not reentrant.
> The read/write functions shall also be called from irq handler (for 
> handling counter overflow).
> So need to use udelay calls. Shall Document it in v2.

Ok.

> >>> +static const struct of_device_id djtag_of_match[] = {
> >>> +	/* for hip05(D02) cpu die */
> >>> +	{ .compatible = "hisilicon,hip05-cpu-djtag-v1",
> >>> +		.data = (void *)djtag_readwrite_v1 },
> >>> +	/* for hip05(D02) io die */
> >>> +	{ .compatible = "hisilicon,hip05-io-djtag-v1",
> >>> +		.data = (void *)djtag_readwrite_v1 },
> >>> +	/* for hip06(D03) cpu die */
> >>> +	{ .compatible = "hisilicon,hip06-cpu-djtag-v1",
> >>> +		.data = (void *)djtag_readwrite_v1 },
> >>> +	/* for hip06(D03) io die */
> >>> +	{ .compatible = "hisilicon,hip06-io-djtag-v2",
> >>> +		.data = (void *)djtag_readwrite_v2 },
> >>> +	/* for hip07(D05) cpu die */
> >>> +	{ .compatible = "hisilicon,hip07-cpu-djtag-v2",
> >>> +		.data = (void *)djtag_readwrite_v2 },
> >>> +	/* for hip07(D05) io die */
> >>> +	{ .compatible = "hisilicon,hip07-io-djtag-v2",
> >>> +		.data = (void *)djtag_readwrite_v2 },
> >>> +	{},
> >>> +};
> >>
> >> If these are backwards compatible, just mark them as compatible in DT,
> >> e.g. hip06 can use
> >>
> >> 	compatible = "hisilicon,hip06-cpu-djtag-v1", "hisilicon,hip05-cpu-djtag-v1";
> >>
> >> so you can tell the difference if you need to, but the driver only has to
> >> list the oldest one here.
> >>
> >> What is the difference between the cpu and io djtag interfaces?
> On some chips like hip06, the djtag version is different for IO die.

In what way? The driver doesn't seem to care about the difference.

	Arnd

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Thread

[PATCH v1 00/11] perf: arm64: Support for Hisilicon SoC Hardware event counters Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 09/11] perf: hisi: Miscellanous node(MN) event counting in perf Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 02/11] dt-bindings: hisi: Add Hisilicon HiP05/06/07 Sysctrl and Djtag dts bindings Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 06/11] perf: hisi: Update Kconfig for Hisilicon PMU support Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 10/11] perf: hisi: Support for Hisilicon DDRC PMU. Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 08/11] perf: hisi: Add sysfs attributes for L3 cache(L3C) PMU Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 04/11] Documentation: perf: hisi: Documentation for HIP05/06/07 PMU event counting. Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 01/11] arm64: MAINTAINERS: hisi: Add hisilicon SoC PMU support Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
    Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Arnd Bergmann <arnd@arndb.de> - 2016-11-07 14:30 +0100
      Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver John Garry <john.garry@huawei.com> - 2016-11-07 15:20 +0100
        Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Arnd Bergmann <arnd@arndb.de> - 2016-11-07 21:10 +0100
          Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver John Garry <john.garry@huawei.com> - 2016-11-08 12:40 +0100
            Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Arnd Bergmann <arnd@arndb.de> - 2016-11-08 12:50 +0100
              Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver John Garry <john.garry@huawei.com> - 2016-11-08 15:00 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Arnd Bergmann <arnd@arndb.de> - 2016-11-08 16:20 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver John Garry <john.garry@huawei.com> - 2016-11-08 16:20 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-09 12:00 +0100
              Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-08 17:00 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver John Garry <john.garry@huawei.com> - 2016-11-09 10:10 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-11 11:40 +0100
      Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Tan Xiaojun <tanxiaojun@huawei.com> - 2016-11-08 08:10 +0100
        Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-08 08:40 +0100
          Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Arnd Bergmann <arnd@arndb.de> - 2016-11-08 12:50 +0100
            Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-08 14:50 +0100
              Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Arnd Bergmann <arnd@arndb.de> - 2016-11-08 16:20 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-09 05:30 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver Arnd Bergmann <arnd@arndb.de> - 2016-11-09 22:50 +0100
                Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon  Djtag driver Anurup M <anurupvasu@gmail.com> - 2016-11-11 11:30 +0100
  [PATCH v1 07/11] perf: hisi: Add support for Hisilicon SoC event counters Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100
  [PATCH v1 05/11] dt-bindings: perf: hisi: Add Devicetree bindings for Hisilicon SoC PMU Anurup M <anurupvasu@gmail.com> - 2016-11-02 16:50 +0100

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