Subject: Re: Is it safe to use these Linux function (test_bit(), set_bit(), clear_bit()) in character device driver for 2.6.10 ppc kernel.

From: Misbah khan <[email-masked]>
Date: Thu, 27 Sep 2007 21:28:59 -0700 (PDT)

Scott Wood-2 wrote:
> 
> Misbah khan wrote:
>> Hi all I am using "test_bit(),set_bit(),clear_bit() etc" API functions 
>> provided by the Linux kernel. I want to know that if anybody is used it 
>> and have full faith in its operation then please let me know. Driver in 
>> the while loop is calling these API's hence i want to make sure that its 
>> operation will remain stable.
> 
> They're used all over the place.  Is there anything about them that you 
> find suspect?
> 
> -Scott
> 
> I have devloped a character driver for FPGA which is memory mapped and
> using these API's to test a bit , set a bit or to clear a bit in the
> memory for eg :-
> 
> /* poll till data is transfered from sdram to dpram */
> 		while((test_bit(DFR_BUSY,(UINT32 *)(\
> 			(void *)mmap_reg_ptr + DATA_STATUS_REG))==1)\
> 			&& (delay < MAX_DELAY_BUSY))
> 		{
> 			KDEBUG3(" In the Dfr delay loop \n");
> 			mdelay(DELAY);
> 			delay+=DELAY;
> 		}/* End of while(test_bit(FPGA_BUSY,(void *)register name) */
> 
> 		if(delay==MAX_DELAY_BUSY)
> 		{
> 			KDEBUG1("Out of the the Dfr busy loop \n");
> 			return -1;
> 		}
> 
> People working for FPGA are sure that they are not making the bit high
> where in my driver is returning -1 from the kernel space aborting it after
> running for few minutes or so . Please let me know that This function is
> stable and i should tell them that the driver is stable in its operation
> and they should check it from there side.
> 
> Misbah
> 
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> 
> 

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