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

[Ji-Ze Hong (Peter Hong)]

Hi Alan,

One Thousand Gnomes 於 2016/7/29 下午 08:48 寫道:

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

[One Thousand Gnomes]

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.

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

[Peter Hung]

Hi,

Ji-Ze Hong (Peter Hong) 於 2016/5/31 上午 09:33 寫道:

This driver is for Fintek F81532/F81534 USB to Serial Ports IC.



Sorry, I forgot to change the mail title for "PATCH V9". I'll resend a
patch with title "PATCH V9".

Thanks
--
With Best Regards,
Peter Hung
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