Re: USB - Generic Serial device : Unable to read more than 4095 bytes

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On 08/03/2015 10:47 PM, arun k wrote:
> Thank you for the reply
> 
>>> The tty layer is limiting you, just keep reading in a loop until you
>>> run out of data, you should not ever expect to read a specific number of
>>> bytes from a tty device at a time, the read call will tell you the
>>> number that was read properly.
> 
> I tried this method but in my case I found data loss. By changing any buffer size modification in driver side , can we fix this issue ?

The data loss is probably occurring because you have all flow control disabled
and the line speed is too fast for no flow control.

Regards,
Peter Hurley

>>> Please don't use the "generic" driver, it's slow and not the best to
>>> use
> 
> Could you tell me is generic driver is suitable for my application ( My usb device sending data at a rate of 409600 bytes/sec) , ? 
> or do you have any other suggestion for me ?
> 
> My Linux kernel  version is 3.4.35
> 
> Regards,
> Arun
> 
> On Tue, Aug 4, 2015 at 1:13 AM, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx <mailto:gregkh@xxxxxxxxxxxxxxxxxxx>> wrote:
> 
>     On Mon, Aug 03, 2015 at 04:44:07PM +0900, arun k wrote:
>     > Hi ,
>     >
>     > I have a trouble with using usb serial generic device.
>     >  I am using USB - Generic Serial driver for communicating with my usb
>     > device and my embedded device.
> 
>     Please don't use the "generic" driver, it's slow and not the best to
>     use.
> 
>     > My usb device sending data at a rate of 409600 bytes/sec, and in host
>     > side application I tried to read 16384 bytes in one read. But the read
>     > size returning is always  4095
> 
>     The tty layer is limiting you, just keep reading in a loop until you
>     run out of data, you should not ever expect to read a specific number of
>     bytes from a tty device at a time, the read call will tell you the
>     number that was read properly.
> 
>     thanks,
> 
>     greg k-h
> 
> 

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