On Fri, Feb 05, 2010 at 11:54:56AM +0200, Vitaly V. Ch wrote:
> Hi all!
>
> I'm find then ftdi_sio.c in 2.4.37.8 kernel have next bug: if I have
> three ftdi-232 simultaneously connected to middle-loaded host,
> application which use one of them will hung in driver, usually during
> few hour.
Can you look at the version in 2.6.33-rc6, and also in the linux-next
tree? Both of those have changes to this driver already done, and
hopefully this fixes your problem.
> At now i try to revise that driver and also I review driver in 2.6.32
> and do few minor fixes + found out possible buggy place.
>
> ****************************************
> 1) function ftdi_232am_baud_base_to_divisor() in 2.6.32 have next view:
>
> static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> {
> unsigned short int divisor;
> /* divisor shifted 3 bits to the left */
> int divisor3 = base / 2 / baud;
> if ((divisor3 & 0x7) == 7)
> divisor3++; /* round x.7/8 up to x+1 */
> divisor = divisor3 >> 3;
> divisor3 &= 0x7;
> if (divisor3 == 1)
> divisor |= 0xc000; /* 0.125 */
> else if (divisor3 >= 4)
> divisor |= 0x4000; /* 0.5 */
> else if (divisor3 != 0)
> divisor |= 0x8000; /* 0.25 */
> /// @warning possible at this place we have bug
> else if (divisor == 1)
> divisor = 0; /* special case for maximum baud rate */
> return divisor;
> }
>
> but POSSIBLE may be need:
>
> static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> {
> unsigned short int divisor;
> /* divisor shifted 3 bits to the left */
> int divisor3 = base / 2 / baud;
> if ((divisor3 & 0x7) == 7)
> divisor3++; /* round x.7/8 up to x+1 */
> divisor = divisor3 >> 3;
> divisor3 &= 0x7;
> if (divisor3 == 1)
> divisor |= 0xc000; /* 0.125 */
> else if (divisor3 >= 4)
> divisor |= 0x4000; /* 0.5 */
> else if (divisor3 != 0)
> divisor |= 0x8000; /* 0.25 */
>
> if (divisor == 1)
> divisor = 0; /* special case for maximum baud rate */
> return divisor;
> }
>
> Can anyone guide me?
I don't know, what is the problem you are seeing here?
> *********************************************************
> 2) In the attached patch I do few small fixes. About half of them must
> be merged into kernel trunk
Which half? :)
Can you look at the above mentioned kernel versions and see if the
problem is already fixed there?
If not, can you send a patch that I can apply (read
Documentation/SubmittingPatches for how to do it)?
thanks,
greg k-h
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