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Date:   Thu, 11 Jun 2020 19:21:58 -0500
From:   Suman Anna <s-anna@...com>
To:     Paul Cercueil <paul@...pouillou.net>
CC:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        Arnaud Pouliquen <arnaud.pouliquen@...com>, <od@...c.me>,
        <linux-remoteproc@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>
Subject: Re: [PATCH v7 4/5] remoteproc: ingenic: Added remoteproc driver

Hi Paul,

On 6/11/20 5:21 PM, Paul Cercueil wrote:
> Hi Suman,
> 
> Le jeu. 11 juin 2020 à 16:47, Suman Anna <s-anna@...com> a écrit :
>> Hi Paul,
>>
>> On 5/15/20 5:43 AM, Paul Cercueil wrote:
>>> This driver is used to boot, communicate with and load firmwares to the
>>> MIPS co-processor found in the VPU hardware of the JZ47xx SoCs from
>>> Ingenic.
>>
>> I have a few comments w.r.t pm_runtime usage in this driver.
>>
>>>
>>> Signed-off-by: Paul Cercueil <paul@...pouillou.net>
>>> Acked-by: Mathieu Poirier <mathieu.poirier@...aro.org>
>>> ---
>>>
>>> Notes:
>>>      v2: Remove exception for always-mapped memories
>>>      v3: - Use clk_bulk API
>>>          - Move device-managed code to its own patch [3/4]
>>>          - Move devicetree table right above ingenic_rproc_driver
>>>          - Removed #ifdef CONFIG_OF around devicetree table
>>>          - Removed .owner = THIS_MODULE in ingenic_rproc_driver
>>>          - Removed useless platform_set_drvdata()
>>>      v4: - Add fix reported by Julia
>>>          - Change Kconfig symbol to INGENIC_VPU_RPROC
>>>          - Add documentation to struct vpu
>>>          - disable_irq_nosync() -> disable_irq()
>>>      v5: No change
>>>      v6: Instead of prepare/unprepare callbacks, use PM runtime 
>>> callbacks
>>>      v7: - Remove use of of_match_ptr()
>>>          - Move Kconfig symbol so that it's in alphabetical order
>>>          - Add missing doc for private structure field aux_base
>>>          - Don't check for (len <= 0) in da_to_va()
>>>          - Add missing \n in dev_info/dev_err messages
>>>
>>>   drivers/remoteproc/Kconfig         |   9 +
>>>   drivers/remoteproc/Makefile        |   1 +
>>>   drivers/remoteproc/ingenic_rproc.c | 280 +++++++++++++++++++++++++++++
>>>   3 files changed, 290 insertions(+)
>>>   create mode 100644 drivers/remoteproc/ingenic_rproc.c
>>>
>>> diff --git a/drivers/remoteproc/Kconfig b/drivers/remoteproc/Kconfig
>>> index fbaed079b299..c4d1731295eb 100644
>>> --- a/drivers/remoteproc/Kconfig
>>> +++ b/drivers/remoteproc/Kconfig
>>> @@ -23,6 +23,15 @@ config IMX_REMOTEPROC
>>>           It's safe to say N here.
>>>   +config INGENIC_VPU_RPROC
>>> +    tristate "Ingenic JZ47xx VPU remoteproc support"
>>> +    depends on MIPS || COMPILE_TEST
>>> +    help
>>> +      Say y or m here to support the VPU in the JZ47xx SoCs from 
>>> Ingenic.
>>> +
>>> +      This can be either built-in or a loadable module.
>>> +      If unsure say N.
>>> +
>>>   config MTK_SCP
>>>       tristate "Mediatek SCP support"
>>>       depends on ARCH_MEDIATEK
>>> diff --git a/drivers/remoteproc/Makefile b/drivers/remoteproc/Makefile
>>> index 0effd3825035..e8b886e511f0 100644
>>> --- a/drivers/remoteproc/Makefile
>>> +++ b/drivers/remoteproc/Makefile
>>> @@ -10,6 +10,7 @@ remoteproc-y                += remoteproc_sysfs.o
>>>   remoteproc-y                += remoteproc_virtio.o
>>>   remoteproc-y                += remoteproc_elf_loader.o
>>>   obj-$(CONFIG_IMX_REMOTEPROC)        += imx_rproc.o
>>> +obj-$(CONFIG_INGENIC_VPU_RPROC)        += ingenic_rproc.o
>>>   obj-$(CONFIG_MTK_SCP)            += mtk_scp.o mtk_scp_ipi.o
>>>   obj-$(CONFIG_OMAP_REMOTEPROC)        += omap_remoteproc.o
>>>   obj-$(CONFIG_WKUP_M3_RPROC)        += wkup_m3_rproc.o
>>> diff --git a/drivers/remoteproc/ingenic_rproc.c 
>>> b/drivers/remoteproc/ingenic_rproc.c
>>> new file mode 100644
>>> index 000000000000..189020d77b25
>>> --- /dev/null
>>> +++ b/drivers/remoteproc/ingenic_rproc.c
>>> @@ -0,0 +1,280 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +/*
>>> + * Ingenic JZ47xx remoteproc driver
>>> + * Copyright 2019, Paul Cercueil <paul@...pouillou.net>
>>> + */
>>> +
>>> +#include <linux/bitops.h>
>>> +#include <linux/clk.h>
>>> +#include <linux/err.h>
>>> +#include <linux/interrupt.h>
>>> +#include <linux/io.h>
>>> +#include <linux/module.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/pm_runtime.h>
>>> +#include <linux/remoteproc.h>
>>> +
>>> +#include "remoteproc_internal.h"
>>> +
>>> +#define REG_AUX_CTRL        0x0
>>> +#define REG_AUX_MSG_ACK        0x10
>>> +#define REG_AUX_MSG        0x14
>>> +#define REG_CORE_MSG_ACK    0x18
>>> +#define REG_CORE_MSG        0x1C
>>> +
>>> +#define AUX_CTRL_SLEEP        BIT(31)
>>> +#define AUX_CTRL_MSG_IRQ_EN    BIT(3)
>>> +#define AUX_CTRL_NMI_RESETS    BIT(2)
>>> +#define AUX_CTRL_NMI        BIT(1)
>>> +#define AUX_CTRL_SW_RESET    BIT(0)
>>> +
>>> +struct vpu_mem_map {
>>> +    const char *name;
>>> +    unsigned int da;
>>> +};
>>> +
>>> +struct vpu_mem_info {
>>> +    const struct vpu_mem_map *map;
>>> +    unsigned long len;
>>> +    void __iomem *base;
>>> +};
>>> +
>>> +static const struct vpu_mem_map vpu_mem_map[] = {
>>> +    { "tcsm0", 0x132b0000 },
>>> +    { "tcsm1", 0xf4000000 },
>>> +    { "sram",  0x132f0000 },
>>> +};
>>> +
>>> +/**
>>> + * struct vpu - Ingenic VPU remoteproc private structure
>>> + * @irq: interrupt number
>>> + * @clks: pointers to the VPU and AUX clocks
>>> + * @aux_base: raw pointer to the AUX interface registers
>>> + * @mem_info: array of struct vpu_mem_info, which contain the 
>>> mapping info of
>>> + *            each of the external memories
>>> + * @dev: private pointer to the device
>>> + */
>>> +struct vpu {
>>> +    int irq;
>>> +    struct clk_bulk_data clks[2];
>>> +    void __iomem *aux_base;
>>> +    struct vpu_mem_info mem_info[ARRAY_SIZE(vpu_mem_map)];
>>> +    struct device *dev;
>>> +};
>>> +
>>> +static int ingenic_rproc_start(struct rproc *rproc)
>>> +{
>>> +    struct vpu *vpu = rproc->priv;
>>> +    u32 ctrl;
>>> +
>>> +    enable_irq(vpu->irq);
>>> +
>>> +    /* Reset the AUX and enable message IRQ */
>>> +    ctrl = AUX_CTRL_NMI_RESETS | AUX_CTRL_NMI | AUX_CTRL_MSG_IRQ_EN;
>>> +    writel(ctrl, vpu->aux_base + REG_AUX_CTRL);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int ingenic_rproc_stop(struct rproc *rproc)
>>> +{
>>> +    struct vpu *vpu = rproc->priv;
>>> +
>>> +    disable_irq(vpu->irq);
>>> +
>>> +    /* Keep AUX in reset mode */
>>> +    writel(AUX_CTRL_SW_RESET, vpu->aux_base + REG_AUX_CTRL);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static void ingenic_rproc_kick(struct rproc *rproc, int vqid)
>>> +{
>>> +    struct vpu *vpu = rproc->priv;
>>> +
>>> +    writel(vqid, vpu->aux_base + REG_CORE_MSG);
>>> +}
>>> +
>>> +static void *ingenic_rproc_da_to_va(struct rproc *rproc, u64 da, 
>>> size_t len)
>>> +{
>>> +    struct vpu *vpu = rproc->priv;
>>> +    void __iomem *va = NULL;
>>> +    unsigned int i;
>>> +
>>> +    for (i = 0; i < ARRAY_SIZE(vpu_mem_map); i++) {
>>> +        const struct vpu_mem_info *info = &vpu->mem_info[i];
>>> +        const struct vpu_mem_map *map = info->map;
>>> +
>>> +        if (da >= map->da && (da + len) < (map->da + info->len)) {
>>> +            va = info->base + (da - map->da);
>>> +            break;
>>> +        }
>>> +    }
>>> +
>>> +    return (__force void *)va;
>>> +}
>>> +
>>> +static struct rproc_ops ingenic_rproc_ops = {
>>> +    .start = ingenic_rproc_start,
>>> +    .stop = ingenic_rproc_stop,
>>> +    .kick = ingenic_rproc_kick,
>>> +    .da_to_va = ingenic_rproc_da_to_va,
>>> +};
>>> +
>>> +static irqreturn_t vpu_interrupt(int irq, void *data)
>>> +{
>>> +    struct rproc *rproc = data;
>>> +    struct vpu *vpu = rproc->priv;
>>> +    u32 vring;
>>> +
>>> +    vring = readl(vpu->aux_base + REG_AUX_MSG);
>>> +
>>> +    /* Ack the interrupt */
>>> +    writel(0, vpu->aux_base + REG_AUX_MSG_ACK);
>>> +
>>> +    return rproc_vq_interrupt(rproc, vring);
>>> +}
>>> +
>>> +static void ingenic_rproc_disable_clks(void *data)
>>> +{
>>> +    struct vpu *vpu = data;
>>> +
>>> +    pm_runtime_resume(vpu->dev);
>>> +    pm_runtime_disable(vpu->dev);
>>> +
>>> +    clk_bulk_disable_unprepare(ARRAY_SIZE(vpu->clks), vpu->clks);
>>> +}
>>> +
>>> +static int ingenic_rproc_probe(struct platform_device *pdev)
>>> +{
>>> +    struct device *dev = &pdev->dev;
>>> +    struct resource *mem;
>>> +    struct rproc *rproc;
>>> +    struct vpu *vpu;
>>> +    unsigned int i;
>>> +    int ret;
>>> +
>>> +    rproc = devm_rproc_alloc(dev, "ingenic-vpu",
>>> +                 &ingenic_rproc_ops, NULL, sizeof(*vpu));
>>> +    if (!rproc)
>>> +        return -ENOMEM;
>>> +
>>> +    vpu = rproc->priv;
>>> +    vpu->dev = &pdev->dev;
>>> +    platform_set_drvdata(pdev, vpu);
>>> +
>>> +    mem = platform_get_resource_byname(pdev, IORESOURCE_MEM, "aux");
>>> +    vpu->aux_base = devm_ioremap_resource(dev, mem);
>>> +    if (IS_ERR(vpu->aux_base)) {
>>> +        dev_err(dev, "Failed to ioremap\n");
>>> +        return PTR_ERR(vpu->aux_base);
>>> +    }
>>> +
>>> +    for (i = 0; i < ARRAY_SIZE(vpu_mem_map); i++) {
>>> +        mem = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>>> +                           vpu_mem_map[i].name);
>>> +
>>> +        vpu->mem_info[i].base = devm_ioremap_resource(dev, mem);
>>> +        if (IS_ERR(vpu->mem_info[i].base)) {
>>> +            ret = PTR_ERR(vpu->mem_info[i].base);
>>> +            dev_err(dev, "Failed to ioremap\n");
>>> +            return ret;
>>> +        }
>>> +
>>> +        vpu->mem_info[i].len = resource_size(mem);
>>> +        vpu->mem_info[i].map = &vpu_mem_map[i];
>>> +    }
>>> +
>>> +    vpu->clks[0].id = "vpu";
>>> +    vpu->clks[1].id = "aux";
>>> +
>>> +    ret = devm_clk_bulk_get(dev, ARRAY_SIZE(vpu->clks), vpu->clks);
>>> +    if (ret) {
>>> +        dev_err(dev, "Failed to get clocks\n");
>>> +        return ret;
>>> +    }
>>> +
>>> +    vpu->irq = platform_get_irq(pdev, 0);
>>> +    if (vpu->irq < 0)
>>> +        return vpu->irq;
>>> +
>>> +    ret = devm_request_irq(dev, vpu->irq, vpu_interrupt, 0, "VPU", 
>>> rproc);
>>> +    if (ret < 0) {
>>> +        dev_err(dev, "Failed to request IRQ\n");
>>> +        return ret;
>>> +    }
>>> +
>>> +    disable_irq(vpu->irq);
>>> +
>>> +    /* The clocks must be enabled for the firmware to be loaded in 
>>> TCSM */
>>> +    ret = clk_bulk_prepare_enable(ARRAY_SIZE(vpu->clks), vpu->clks);
>>> +    if (ret) {
>>> +        dev_err(dev, "Unable to start clocks\n");
>>> +        return ret;
>>> +    }
>>
>> You are enabling the clocks directly here and also trying to manage 
>> them through pm_runtime callbacks again.
> 
> Yes. The clocks need to be enabled in the probe.

For the preferred non CONFIG_PM case now and lack of prepare/unprepare().

> 
>>> +
>>> +    pm_runtime_irq_safe(dev);
>>
>> Nothing wrong with this, but this does take an additional reference 
>> count on the parent device (a bus device for you??), and also implies 
>> that your clk driver code can all run in atomic context so unless you 
>> have a strong reason, it is safe to drop this.
> 
> The clock driver code can run in atomic context, it is guaranteed by the 
> clk API.

OK.

> 
>>
>>> +    pm_runtime_set_active(dev);
>>
>> The get_sync below would have been sufficient if you had either 
>> limited the clk API above to just clk_prepare, or you could have moved 
>> the whole clk API above into your runtime resume callback.
> 
> You assume that pm_runtime_get() will enable the clocks, but that's only 
> true if CONFIG_PM is set.
> 
> The reason the clocks are enabled in the probe, and 
> pm_runtime_set_active() is called, is that it works whether or not 
> CONFIG_PM is set.

As I said, if the intention is to reflect the clocks active state in rpm 
status, then pm_runtime_get_noresume() does the job for you instead of 
get_sync(). pm_runtime_get_sync() typically does 3 things - increment 
the usage count, invoke your callbacks (enable clocks for you), and sets 
the status to active, with the last two steps optional depending on 
usage count.

> 
>>> +    pm_runtime_enable(dev);
>>> +    pm_runtime_get_sync(dev);
>>
>> If the intention was to increment the usage count with the above 
>> sequence, pm_runtime_get_noresume() is better. But dropping all of the 
>> above and just using get_sync would have been sufficient.
>>
>>> +    pm_runtime_use_autosuspend(dev);
>>
>> I don't see any setting of the autosuspend delay (default value is 0). 
>> So, you might have as well just not used this at all, and just used 
>> pm_runtime_put() below.
> 
> Autosuspend delay value can be set from userspace.

Yes, but I don't see a specific purpose for it in your driver. Either 
you have remoteproc running (and so clocks enabled always), or you don't 
have a firmware loaded and want clocks disabled (not sure you would want 
to waste power for certain of amount of time).

> 
>>> +
>>> +    ret = devm_add_action_or_reset(dev, ingenic_rproc_disable_clks, 
>>> vpu);
>>> +    if (ret) {
>>> +        dev_err(dev, "Unable to register action\n");
>>> +        goto out_pm_put;
>>> +    }
>>> +
>>> +    ret = devm_rproc_add(dev, rproc);
>>> +    if (ret) {
>>> +        dev_err(dev, "Failed to register remote processor\n");
>>> +        goto out_pm_put;
>>> +    }
>>
>> You are using auto-boot, so the firmware loading is an asynchronous 
>> event and most probably you would run through below sequence first, 
>> and end up disabling the clocks with an incorrect rpm status.
> 
> The driver can auto-load the firmware, but that does not mean it will. 
> We actually don't do that, and load a task-specific firmware onto the 
> remote processor on demand.

Yeah OK, depends on what is preferred by default. If it is more standard 
practise that the remoteproc is booted by userspace always, then I 
suggest setting auto_boot as false. But nothing wrong with expecting to 
boot by default with a starting firmware.

> 
>>> +
>>> +out_pm_put:
>>> +    pm_runtime_put_autosuspend(dev);
>>
>> And finally, with the remoteproc core rpm patch, this would all have 
>> been unnecessary.
>>
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +static const struct of_device_id ingenic_rproc_of_matches[] = {
>>> +    { .compatible = "ingenic,jz4770-vpu-rproc", },
>>> +    {}
>>> +};
>>> +MODULE_DEVICE_TABLE(of, ingenic_rproc_of_matches);
>>> +
>>> +static int __maybe_unused ingenic_rproc_suspend(struct device *dev)
>>> +{
>>> +    struct vpu *vpu = dev_get_drvdata(dev);
>>> +
>>> +    clk_bulk_disable(ARRAY_SIZE(vpu->clks), vpu->clks);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int __maybe_unused ingenic_rproc_resume(struct device *dev)
>>> +{
>>> +    struct vpu *vpu = dev_get_drvdata(dev);
>>> +
>>> +    return clk_bulk_enable(ARRAY_SIZE(vpu->clks), vpu->clks);
>>> +}
>>> +
>>> +static const struct dev_pm_ops __maybe_unused ingenic_rproc_pm = {
>>> +    SET_RUNTIME_PM_OPS(ingenic_rproc_suspend, ingenic_rproc_resume, 
>>> NULL)
>>> +};
>>> +
>>> +static struct platform_driver ingenic_rproc_driver = {
>>> +    .probe = ingenic_rproc_probe,
>>> +    .driver = {
>>> +        .name = "ingenic-vpu",
>>> +#ifdef CONFIG_PM
>>
>> Not sure why you would want to maintain this conditional, because 
>> runtime_pm is a core dependency now for your driver to work properly.
> 
> No, it is not - the driver works perfectly fine with CONFIG_PM being 
> disabled, and having a hardcoded dependency on CONFIG_PM is not 
> something we want.

OK, so if IIUC, in general CONFIG_PM is not a typical usage for your 
MIPS platforms. Your driver is the first non-ARM remoteproc driver :), 
CONFIG_PM is almost a given on most ARM platforms.

So, I fail to see how your clocks can stay disabled then when 
CONFIG_PM=n if the remoteproc fails to load with the current code, which 
was your primary argument for using prepare/unprepare (based on comments 
on prior versions). It looks to me that your needs are indeed better 
suited with the prepare/unprepare ops as in your initial series.

And in the case of CONFIG_PM=y, you have three levels of code that 
enables the clocks (the bare clk API, the pm_runtime_get in probe, and 
the pm_runtime_get in the remoteproc core). Depending on the rpm status, 
it may or may not invoke the callbacks.

regards
Suman

> 
> Cheers,
> -Paul
> 
>> regards
>> Suman
>>
>>> +        .pm = &ingenic_rproc_pm,
>>> +#endif
>>> +        .of_match_table = ingenic_rproc_of_matches,
>>> +    },
>>> +};
>>> +module_platform_driver(ingenic_rproc_driver);
>>> +
>>> +MODULE_LICENSE("GPL");
>>> +MODULE_AUTHOR("Paul Cercueil <paul@...pouillou.net>");
>>> +MODULE_DESCRIPTION("Ingenic JZ47xx Remote Processor control driver");
>>>
>>
> 
> 

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