Re: [PATCH] usb:serial: Add Fintek F81532/534 driver

[Ji-Ze Hong (Peter Hong)]

Hi Alan,

One Thousand Gnomes æ 2016/7/29 äå 08:48 åé:
> O
> > +static int f81534_set_normal_register(struct usb_device *dev, u16 reg, u8 data)
> > +{
> > +	size_t count = F81534_USB_MAX_RETRY;
> > +	int status;
> > +	u8 *tmp;
> > +
> > +	tmp = kmalloc(sizeof(u8), GFP_KERNEL);
> > +	if (!tmp)
> > +		return -ENOMEM;
>
> You end up doing huge numbers of tiny allocation and frees in some of the
> code paths. I think it would be better to allocate them at a higher level
> as they are not that cheap on CPU time.
>
> > +static int f81534_read_data(struct usb_serial *usbserial, u32 address,
> > +				size_t size, unsigned char *buf)
> > +{
>
> Is a particularly good example - you do 4 mallocs plus two per byte of
> data.

I'll re-factor the newest V9 patch with your suggestion. To malloc a
byte within usb_serial privates, and make a mutex to protect it.

I'll send it as V10 when I tested it.

Thanks for your suggestion.
--
With Best Regards,
Peter Hong