Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Feedback-ID: i0e894699:Fastmail
Date:   Thu, 1 Sep 2022 22:04:43 +0300
From:   Dafna Hirschfeld <dafna@fastmail.com>
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Jiho Chu <jiho.chu@samsung.com>, arnd@arndb.de,
        linux-kernel@vger.kernel.org, yelini.jeong@samsung.com,
        myungjoo.ham@samsung.com
Subject: Re: [PATCH 1/9] trinity: Add base driver
Message-ID: <20220901190443.d6b42mtmzju354b5@guri>
References: <20220725065308.2457024-1-jiho.chu@samsung.com>
 <CGME20220725065309epcas1p4565e7bb0fea1aaf3e5e300de00774c2a@epcas1p4.samsung.com>
 <20220725065308.2457024-2-jiho.chu@samsung.com>
 <YuE8JNjIBNdg/kkX@kroah.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Disposition: inline
In-Reply-To: <YuE8JNjIBNdg/kkX@kroah.com>
Precedence: bulk

On 27.07.2022 15:22, Greg KH wrote:
>On Mon, Jul 25, 2022 at 03:53:00PM +0900, Jiho Chu wrote:
>> It contains the base codes for trinity driver. Minimal codes to load and
>> probe device is provided. The Trinity Family is controlled by the
>> Memory-Mapped Registers, the register addresses and offsets are
>> described. And user api interfaces are presented to control device under
>> ioctl manner.
>>
>> Signed-off-by: Jiho Chu <jiho.chu@samsung.com>
>> Signed-off-by: yelini-jeong <yelini.jeong@samsung.com>
>> Signed-off-by: Dongju Chae <dongju.chae@samsung.com>
>> Signed-off-by: Parichay Kapoor <pk.kapoor@samsung.com>
>> Signed-off-by: Wook Song <wook16.song@samsung.com>
>> Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
>> ---
>>  drivers/misc/Kconfig                        |   1 +
>>  drivers/misc/Makefile                       |   1 +
>>  drivers/misc/trinity/Kconfig                |  27 ++
>>  drivers/misc/trinity/Makefile               |   7 +
>>  drivers/misc/trinity/trinity.c              | 369 ++++++++++++++
>>  drivers/misc/trinity/trinity_common.h       | 392 +++++++++++++++
>>  drivers/misc/trinity/trinity_vision2_drv.c  | 512 ++++++++++++++++++++
>>  drivers/misc/trinity/trinity_vision2_regs.h | 210 ++++++++
>>  include/uapi/misc/trinity.h                 | 458 +++++++++++++++++
>>  9 files changed, 1977 insertions(+)
>>  create mode 100644 drivers/misc/trinity/Kconfig
>>  create mode 100644 drivers/misc/trinity/Makefile
>>  create mode 100644 drivers/misc/trinity/trinity.c
>>  create mode 100644 drivers/misc/trinity/trinity_common.h
>>  create mode 100644 drivers/misc/trinity/trinity_vision2_drv.c
>>  create mode 100644 drivers/misc/trinity/trinity_vision2_regs.h
>>  create mode 100644 include/uapi/misc/trinity.h
>>
>> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
>> index 41d2bb0ae23a..ad0d5f6af291 100644
>> --- a/drivers/misc/Kconfig
>> +++ b/drivers/misc/Kconfig
>> @@ -500,4 +500,5 @@ source "drivers/misc/cardreader/Kconfig"
>>  source "drivers/misc/habanalabs/Kconfig"
>>  source "drivers/misc/uacce/Kconfig"
>>  source "drivers/misc/pvpanic/Kconfig"
>> +source "drivers/misc/trinity/Kconfig"
>>  endmenu
>> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
>> index 70e800e9127f..c63f3fc89780 100644
>> --- a/drivers/misc/Makefile
>> +++ b/drivers/misc/Makefile
>> @@ -60,3 +60,4 @@ obj-$(CONFIG_XILINX_SDFEC)	+= xilinx_sdfec.o
>>  obj-$(CONFIG_HISI_HIKEY_USB)	+= hisi_hikey_usb.o
>>  obj-$(CONFIG_HI6421V600_IRQ)	+= hi6421v600-irq.o
>>  obj-$(CONFIG_OPEN_DICE)		+= open-dice.o
>> +obj-$(CONFIG_TRINITY)		+= trinity/
>> diff --git a/drivers/misc/trinity/Kconfig b/drivers/misc/trinity/Kconfig
>> new file mode 100644
>> index 000000000000..ad4bab78f7c6
>> --- /dev/null
>> +++ b/drivers/misc/trinity/Kconfig
>> @@ -0,0 +1,27 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +
>> +config TRINITY
>> +	bool "Samsung Neural Processing Unit"
>> +	depends on HAS_IOMEM
>> +	depends on HAS_DMA
>> +	default n
>
>The default is 'n', no need to ever say it again.
>
>> +	help
>> +	  Select this option to enable driver support for Samsung
>> +	  Neural Processing Unit (NPU).
>> +
>> +	  This driver works as a base driver of the other drivers
>> +	  for Trinity device family.
>> +
>> +	  This option should be enabled to support Trinity
>> +	  Vision 2 (TRIV2), and Trinity Audio (TRIA).
>> +
>> +config TRINITY_VISION2
>> +	tristate "Samsung NPU Trinity Vision 2"
>
>What happened to "vision 1"?
>
>> +	depends on TRINITY
>> +	default n
>> +	help
>> +	  Select this option to enable driver support for a Samsung
>> +	  Neural Processing Unit (NPU), Tinity Vision 2.
>> +
>> +	  This driver enables userspace system library to access the
>> +	  device via /dev/triv2-N.
>
>What is the module name?
>
>Where is the userspace library code that talks to this?  Any
>documentation for this interface anywhere?
>
>> +#define BASE_DEV_NAME "trinity"
>
>KBUILD_MODNAME?
>
>> +/* A global lock for shared static variables such as dev_bitmap */
>> +static DEFINE_SPINLOCK(trinity_lock);
>
>That's a sign something is wrong, you should not need any module-wide
>code variables.
>
>> +/* A bitmap to keep track of active Trinity devices */
>> +static unsigned long dev_bitmap[TRINITY_DEV_END];
>
>Should not be needed, use a simple ida structure if you really want to
>name things cleanly.
>
>> +
>> +/**
>> + * trinity_release() - A common callback for close() in file_operations for a
>> + *		Trinity	device node. If there are device-specific data to be
>> + *		cleaned-up, it is required to clean them up before invoke this
>> + *		callback.
>> + *
>> + * @inode: Inode to be closed
>> + * @file: File to be closed
>> + *
>> + * Returns 0 on success. Otherwise, returns negative error.
>> + */
>> +int trinity_release(struct inode *inode, struct file *file)
>> +{
>> +	struct trinity_driver *drv;
>> +
>> +	drv = file->private_data;
>> +
>> +	if (drv->verbose)
>> +		dev_info(drv_to_dev_ptr(drv), "%s\n", "Device closed");
>> +
>> +	mutex_lock(&drv->lock);
>> +	drv->opened = drv->opened - 1;
>
>That will never work, you can't keep track of open/close calls.

Hi, can you explain why this will not work?

Thanks,
Dafna

>
>> +	if (drv->opened == 0) {
>> +		/* wait already submitted requests */
>> +		if (drv->desc->drain_reqs)
>> +			drv->desc->drain_reqs(drv);
>> +
>> +		drv->desc->set_state(drv, TRINITY_STATE_PAUSE);
>> +	}
>> +	mutex_unlock(&drv->lock);
>> +
>> +	return 0;
>> +}
>> +
>> +static bool trinity_is_empty(void)
>> +{
>> +	enum trinity_dev_type type;
>> +	bool empty = true;
>> +
>> +	spin_lock(&trinity_lock);
>> +	for (type = TRINITY_DEV_UNKNOWN, type++; type < TRINITY_DEV_END;
>> +	     type++) {
>> +		if (find_first_bit(&dev_bitmap[type], TRINITY_DEV_EACH_MAX) !=
>> +		    TRINITY_DEV_EACH_MAX) {
>> +			empty = false;
>> +			break;
>> +		}
>> +	}
>> +	spin_unlock(&trinity_lock);
>> +
>> +	return empty;
>> +}
>> +
>> +/**
>> + * trinity_wait_ready() - Wait until trinity is ready state
>> + *
>> + * @drv: an instance of trinity driver
>> + *
>> + * Returns 0 on success. Otherwise, returns negative error.
>> + */
>> +int trinity_wait_ready(struct trinity_driver *drv)
>> +{
>> +	const unsigned long time_out = HZ / 100UL; /* 1/100 seconds*/
>> +	const unsigned int max_retry = 10;
>> +	unsigned int retry = 0;
>> +	wait_queue_head_t wq;
>> +
>> +	drv->desc->set_state(drv, TRINITY_STATE_READY);
>> +
>> +	init_waitqueue_head(&wq);
>> +	/* try to ensure that NPU is in the ready state */
>> +	while (wait_event_timeout(
>> +		       wq, drv->desc->get_state(drv) == TRINITY_STATE_READY,
>> +		       time_out) == 0) {
>> +		/* regarded as failure */
>> +		if (retry == max_retry)
>> +			return -ETIMEDOUT;
>> +		retry++;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * trinity_open() - A common callback for open() in file_operations for a Trinity
>> + *		device node. If device-specific open() is required, this
>> + *		callback should be invoked by that open().
>> + *
>> + * @inode: inode to be opened
>> + * @f: file to be opened
>> + *
>> + * Returns 0 on success. Otherwise, returns negative error.
>> + */
>> +int trinity_open(struct inode *inode, struct file *f)
>> +{
>> +	struct miscdevice *miscdev;
>> +	struct trinity_driver *drv;
>> +	int ret = 0;
>> +
>> +	miscdev = (struct miscdevice *)f->private_data;
>
>Why the cast?
>
>> +	drv = container_of(miscdev, struct trinity_driver, mdev);
>> +	f->private_data = drv;
>> +
>> +	mutex_lock(&drv->lock);
>> +	/** remove PAUSE set on the CP of the NPU */
>> +	if (drv->opened == 0) {
>> +		ret = trinity_wait_ready(drv);
>> +		if (ret != 0)
>> +			goto out;
>> +	}
>> +	drv->opened = drv->opened + 1;
>
>Again, trying to keep track of open/close calls will never work.  Just
>let the vfs handle that for you (you will note it does that already).
>Your driver should never need to worry about it.
>
>
>> +
>> +	if (drv->verbose)
>> +		dev_info(drv_to_dev_ptr(drv), "%s\n", "Device opened");
>> +
>> +out:
>> +	mutex_unlock(&drv->lock);
>> +
>> +	return 0;
>> +}
>> +
>> +static void trinity_common_init(struct device *dev)
>> +{
>> +	if (!trinity_is_empty())
>> +		return;
>> +
>> +	/* Common init codes */
>> +}
>
>Missing something?
>
>
>> +
>> +static void trinity_common_exit(void)
>> +{
>> +	if (!trinity_is_empty())
>> +		return;
>> +
>> +	/* Common deinit codes */
>> +}
>> +
>
>Don't provide empty functions that do nothing please.
>
>> +static int trinity_set_device_id(struct trinity_driver *drv)
>> +{
>> +	const struct trinity_desc *desc = drv->desc;
>> +	struct device *dev = drv_to_dev_ptr(drv);
>> +	int err = -EEXIST;
>> +
>> +	spin_lock(&trinity_lock);
>> +	drv->dev_id =
>> +		find_first_zero_bit(&dev_bitmap[dev->id], TRINITY_DEV_EACH_MAX);
>
>Again, use an ida structure please.
>
>> +	if (drv->dev_id < TRINITY_DEV_EACH_MAX) {
>> +		set_bit(drv->dev_id, &dev_bitmap[dev->id]);
>> +		err = 0;
>> +	}
>> +	spin_unlock(&trinity_lock);
>> +
>> +	if (err == 0) {
>> +		drv->name = devm_kasprintf(dev, GFP_KERNEL, "%s-%u", desc->type,
>> +					   drv->dev_id);
>> +		err = IS_ERR_OR_NULL(drv->name) ? -ENOMEM : 0;
>
>Spell out if statements, this just makes things hard to read.  And you
>just leaked a "bit" if this failed, so are you sure this was ever
>tested?
>
>
>
>> +	}
>> +
>> +	return err;
>> +}
>> +
>> +int trinity_create_node(struct trinity_driver *drv)
>> +{
>> +	struct device *dev = drv_to_dev_ptr(drv);
>> +	int err;
>> +
>> +	/** register as a misc device */
>> +	drv->mdev.minor = MISC_DYNAMIC_MINOR;
>> +	drv->mdev.parent = NULL;
>
>No parent device?  Why not?  What bus does this device live on?  This is
>a platform device lower on in this code, please use that, don't just
>hang out there at the top of the device tree.
>
>
>> +	drv->mdev.name = drv->name;
>> +
>> +	err = misc_register(&drv->mdev);
>> +	if (err < 0)
>> +		dev_err(dev, "failed to register as a misc device");
>> +	else
>> +		dev_info(dev, "misc device created!");
>
>Again, drivers are quiet if all goes well.
>
>I stopped here.
>
>Also, please remove the layers of abstraction you have in your
>structures that you never use, but yet still define in this patch for
>some reason...
>
>thanks,
>
>greg k-h