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    SubjectRe: [PATCH] Topcliff PHUB: Generate PacketHub driver
    Date
    Hi Arnd,

    I will modify for your comments by today or tomorrow.

    Thanks,
    Ohtake

    ----- Original Message -----
    From: "Arnd Bergmann" <arnd@arndb.de>
    To: "Masayuki Ohtak" <masa-korg@dsn.okisemi.com>
    Cc: "Alan Cox" <alan@lxorguk.ukuu.org.uk>; "LKML" <linux-kernel@vger.kernel.org>; "Andrew"
    <andrew.chih.howe.khor@intel.com>; "Intel OTC" <joel.clark@intel.com>; "Wang, Qi" <qi.wang@intel.com>; "Wang, Yong Y"
    <yong.y.wang@intel.com>
    Sent: Thursday, June 17, 2010 8:59 PM
    Subject: Re: [PATCH] Topcliff PHUB: Generate PacketHub driver


    > Looks almost good to me now. Some more details (only the -EFAULT return code
    > is a real issue, the other ones are cosmetic changes):
    >
    > On Thursday 17 June 2010, Masayuki Ohtak wrote:
    > > +
    > > +#define PCH_READ_REG(a) ioread32(pch_phub_reg.pch_phub_base_address + (a))
    > > +
    > > +#define PCH_WRITE_REG(a, b) iowrite32((a), pch_phub_reg.pch_phub_base_address +\
    > > + (b))
    >
    > I'd recommend just getting rid of these abstractions. You only use
    > them in one or two functions each, so you can just as well add a local
    > variable there and do
    >
    > void __iomem *p = pch_phub_reg.pch_phub_base_address;
    > foo = ioread32(p + foo_offset);
    > bar = ioread32(p + bar_offset);
    > ...
    >
    > Not really important, but this way it would be more conventional
    > without having to write extra code.
    >
    > > +/*--------------------------------------------
    > > + global variables
    > > +--------------------------------------------*/
    > > +/**
    > > + * struct pch_phub_reg_t - PHUB register structure
    > > + * @phub_id_reg: PHUB_ID register val
    > > + * @q_pri_val_reg: QUEUE_PRI_VAL register val
    > > + * @rc_q_maxsize_reg: RC_QUEUE_MAXSIZE register val
    > > + * @bri_q_maxsize_reg: BRI_QUEUE_MAXSIZE register val
    > > + * @comp_resp_timeout_reg: COMP_RESP_TIMEOUT register val
    > > + * @bus_slave_control_reg: BUS_SLAVE_CONTROL_REG register val
    > > + * @deadlock_avoid_type_reg: DEADLOCK_AVOID_TYPE register val
    > > + * @intpin_reg_wpermit_reg0: INTPIN_REG_WPERMIT register 0 val
    > > + * @intpin_reg_wpermit_reg1: INTPIN_REG_WPERMIT register 1 val
    > > + * @intpin_reg_wpermit_reg2: INTPIN_REG_WPERMIT register 2 val
    > > + * @intpin_reg_wpermit_reg3: INTPIN_REG_WPERMIT register 3 val
    > > + * @int_reduce_control_reg: INT_REDUCE_CONTROL registers val
    > > + * @clkcfg_reg: CLK CFG register val
    > > + * @pch_phub_base_address: register base address
    > > + * @pch_phub_extrom_base_address: external rom base address
    > > + * @pch_phub_suspended: PHUB status val
    > > + */
    > > +struct pch_phub_reg_t {
    >
    > It would be better to drop the _t postfix on the type name.
    > By convention, we use this only for typedefs on simple data
    > types like off_t but not for structures.
    >
    > > + __u32 phub_id_reg;
    > > + __u32 q_pri_val_reg;
    > > + __u32 rc_q_maxsize_reg;
    >
    > When I told you to change the ioctl arguments to use __u32 instead
    > of u32, I was only referring to those parts that are in the user-visible
    > section of the header file. While it does not hurt to use __u32 in
    > the kernel, you should understand the distinction.
    >
    > > +/** pch_phub_write - Implements the write functionality of the Packet Hub
    > > + * module.
    > > + * @file: Contains the reference of the file structure
    > > + * @buf: Usermode buffer pointer
    > > + * @size: Usermode buffer size
    > > + * @ppos: Contains the reference of the file structure
    > > + */
    > > +static ssize_t pch_phub_write(struct file *file, const char __user *buf,
    > > + size_t size, loff_t *ppos)
    > > +{
    > > + static __u32 data;
    >
    > No need to make data static.
    >
    > > + __s32 ret_value;
    > > + __u32 addr_offset = 0;
    > > + loff_t pos = *ppos;
    > > +
    > > + if (pos < 0)
    > > + return -EINVAL;
    > > +
    > > + for (addr_offset = 0; addr_offset < size; addr_offset++) {
    > > + get_user(data, &buf[addr_offset]);
    > > +
    > > + ret_value = pch_phub_write_serial_rom(0x80 + addr_offset + pos,
    > > + data);
    > > + if (ret_value)
    > > + return -EFAULT;
    >
    > You should return -EFAULT if the get_user() call fails, otherwise you have
    > a possible security hole. If pch_phub_write_serial_rom fails, the correct
    > return code would be -EIO.
    >
    > > +/**
    > > + * file_operations structure initialization
    > > + */
    > > +static const struct file_operations pch_phub_fops = {
    > > + .owner = THIS_MODULE,
    > > + .read = pch_phub_read,
    > > + .write = pch_phub_write,
    > > + .unlocked_ioctl = pch_phub_ioctl,
    > > +};
    >
    > If would be good to add a line of
    > .llseek = default_llseek,
    > here. I have a patch to change the default llseek method to one
    > that disallows seeking, so if you add this line, there is one
    > less driver for me to patch.
    >
    > Arnd
    >





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