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Message-ID: <20230331222641.38009-1-blarson@amd.com>
Date: Fri, 31 Mar 2023 15:26:41 -0700
From: Brad Larson <blarson@....com>
To: <andy.shevchenko@...il.com>
CC: <adrian.hunter@...el.com>, <alcooperx@...il.com>, <arnd@...db.de>,
<blarson@....com>, <brendan.higgins@...ux.dev>,
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Subject: Re: [PATCH v12 15/15] soc: amd: Add support for AMD Pensando SoC Controller
Hi Andy,
Thanks for the review.
On Thu, Mar 23, 2023 at 13:06 Andy Shevchenko <andy.shevchenko@...il.com> wrote:
> On Thu, Mar 23, 2023 at 2:11 AM Brad Larson <blarson@....com> wrote:
>>
>> The Pensando SoC controller is a SPI connected companion device
>> that is present in all Pensando SoC board designs. The essential
>> board management registers are accessed on chip select 0 with
>> board mgmt IO support accessed using additional chip selects.
>
> ...
>
>> +config AMD_PENSANDO_CTRL
>> + tristate "AMD Pensando SoC Controller"
>> + depends on SPI_MASTER=y
>> + depends on (ARCH_PENSANDO && OF) || COMPILE_TEST
>> + default y if ARCH_PENSANDO
>
> default ARCH_PENSANDO
Changed to default ARCH_PENSANDO
>> + select REGMAP_SPI
>> + select MFD_SYSCON
>
> ...
>
>> +/*
>> + * AMD Pensando SoC Controller
>> + *
>> + * Userspace interface and reset driver support for SPI connected Pensando SoC
>> + * controller device. This device is present in all Pensando SoC designs and
>> + * contains board control/status regsiters and management IO support.
>
> registers ?
Fixed the typo
> ...
>
>> +#include <linux/cdev.h>
>> +#include <linux/delay.h>
>> +#include <linux/device.h>
>> +#include <linux/err.h>
>> +#include <linux/fs.h>
>> +#include <linux/init.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>
> Seems semi-random. Are you sure you use this and not missing mod_devicetable.h?
Added mod_devicetable.h.
Removed delay.h, fs.h and of_device.h
>> +#include <linux/reset-controller.h>
>> +#include <linux/spi/spi.h>
>
>...
>
>> +struct penctrl_device {
>> + struct spi_device *spi_dev;
>> + struct reset_controller_dev rcdev;
>
> Perhaps swapping these two might provide a better code generation.
Its a 96 byte struct with pointer followed by the reset controller.
The spi_device variable is accessed frequently and rcdev during
boot and ideally never again so if rcdev is mostly missing from
cache that is fine. Likely the address of spi_dev is also in
cache given it is periodically accessed.
> ...
>
>> + struct spi_transfer t[2] = { 0 };
>
> 0 is not needed.
Dropped the 0.
> ...
>
>> + if (_IOC_DIR(cmd) & _IOC_READ)
>> + ret = !access_ok((void __user *)arg, _IOC_SIZE(cmd));
>> + else if (_IOC_DIR(cmd) & _IOC_WRITE)
>> + ret = !access_ok((void __user *)arg, _IOC_SIZE(cmd));
>
>
> Maybe you should create a temporary variable as
>
> void __user *in = ... arg;
Yes, created temp variable.
>
>> + if (ret)
>> + return -EFAULT;
>
> ...
>
>> + /* Verify and prepare spi message */
>
> SPI
Changed to SPI
>> + size = _IOC_SIZE(cmd);
>> + if ((size % sizeof(struct penctrl_spi_xfer)) != 0) {
>
> ' != 0' is redundant.
Fixed
>
>> + ret = -EINVAL;
>> + goto done;
>> + }
>> + num_msgs = size / sizeof(struct penctrl_spi_xfer);
>
>> + if (num_msgs == 0) {
>> + ret = -EINVAL;
>> + goto done;
>> + }
>
> Can be unified with a previous check as
>
> if (size == 0 || size % ...)
Yes, made this change.
>> + msg = memdup_user((struct penctrl_spi_xfer __user *)arg, size);
>> + if (!msg) {
>> + ret = PTR_ERR(msg);
>> + goto done;
>> + }
>
>...
>
>> + if (copy_from_user((void *)(uintptr_t)tx_buf,
>> + (void __user *)msg->tx_buf, msg->len)) {
>
> Why are all these castings here?
Yes, overkill, changed to:
if (copy_from_user(tx_buf, (void __user *)msg->tx_buf, msg->len)) {
> ...
>
>> + if (copy_to_user((void __user *)msg->rx_buf,
>> + (void *)(uintptr_t)rx_buf, msg->len))
>> + ret = -EFAULT;
>
> Ditto.
Changed to:
if (copy_to_user((void __user *)msg->rx_buf, rx_buf, msg->len))
> ...
>
>> + struct spi_transfer t[2] = { 0 };
>
> 0 is redundant.
Dropped the 0.
> ...
>
>> + struct spi_transfer t[1] = { 0 };
>
> Ditto.
Dropped the 0.
> Why is this an array?
Fixed, it's a single message and shouldn't be an array.
> ...
>
>> + ret = spi_sync(spi_dev, &m);
>> + return ret;
>
> return spi_sync(...);
Fixed.
> ...
>
>> + np = spi_dev->dev.parent->of_node;
>> + ret = of_property_read_u32(np, "num-cs", &num_cs);
>
> Why not simply device_property_read_u32()?
It can be and removed two lines with below result. Also changed the
variable spi_dev to spi which is the more common usage.
ret = device_property_read_u32(spi->dev.parent, "num-cs", &num_cs);
if (ret)
return dev_err_probe(&spi->dev, ret,
"number of chip-selects not defined\n");
> ...
>
>> + cdev = cdev_alloc();
>> + if (!cdev) {
>> + dev_err(&spi_dev->dev, "allocation of cdev failed");
>> + ret = -ENOMEM;
>
> ret = dev_err_probe(...);
Fixed.
>> + goto cdev_failed;
>> + }
>
> ...
>
>> + ret = cdev_add(cdev, penctrl_devt, num_cs);
>> + if (ret) {
>
>> + dev_err(&spi_dev->dev, "register of cdev failed");
>
> dev_err_probe() ?
Fixed.
>> + goto cdev_delete;
>> + }
>
> ...
>
>> + penctrl = kzalloc(sizeof(*penctrl), GFP_KERNEL);
>> + if (!penctrl) {
>
>> + ret = -ENOMEM;
>> + dev_err(&spi_dev->dev, "allocate driver data failed");
>
> ret = dev_err_probe();
> But we do not print memory allocation failure messages.
Fixed this way
penctrl = kzalloc(sizeof(*penctrl), GFP_KERNEL);
if (!penctrl) {
ret = -ENOMEM;
goto free_cdev;
}
> ...
>
>> + if (IS_ERR(dev)) {
>> + ret = IS_ERR(dev);
>> + dev_err(&spi_dev->dev, "error creating device\n");
>
> ret = dev_err_probe();
Fixed.
> ...
>
> + spi_set_drvdata(spi_dev, penctrl);
>
> Is it in use?
Not used and now dropped.
> ...
>
>> + penctrl->rcdev.of_node = spi_dev->dev.of_node;
>
> device_set_node();
Added: device_set_node(&spi->dev, dev_fwnode(dev));
> ...
>
>> + ret = reset_controller_register(&penctrl->rcdev);
>> + if (ret)
>> + return dev_err_probe(&spi_dev->dev, ret,
>> + "failed to register reset controller\n");
>> + return ret;
>
> return 0;
Yes, changed.
> ...
>
>> + device_destroy(penctrl_class, penctrl_devt);
>
> Are you sure this is the correct API?
Yes, however a probe error could call up to 5 APIs to clean up which resulted
in this update:
destroy_device:
for (cs = 0; cs < num_cs; cs++)
device_destroy(penctrl_class, MKDEV(MAJOR(penctrl_devt), cs));
kfree(penctrl);
free_cdev:
cdev_del(cdev);
destroy_class:
class_destroy(penctrl_class);
unregister_chrdev:
unregister_chrdev(MAJOR(penctrl_devt), "penctrl");
return ret;
> ...
>
>> +#include <linux/types.h>
>> +#include <linux/ioctl.h>
>
> Sorted?
Swapped these
Regards,
Brad
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