lkml.org 
[lkml]   [2011]   [Apr]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] ATA: pata_at91.c bugfixes
On Tue, Apr 26, 2011 at 10:38:04AM +0400, Igor Plyatov wrote:
> >On Wed, Apr 20, 2011 at 03:44:37PM +0400, Igor Plyatov wrote:
> >>* Fix "initial_timing" structure initialisation. The "struct ata_timing" must
> >> contain 10 members, but ".dmack_hold" member was not initialised.
> >>* The AT91SAM9 microcontrollers use special coding scheme for SMC_SETUP,
> >> SMC_PULSE, SMC_CYCLE registers.
> >> Old driver operates correctly only with low master clock values, but
> >> with high master clock it incorrectly calculates SMC values and stops
> >> to operate, because SMC can be setup only to admissible ranges in special
> >> format.
> >> New code correctly calculates SMC registers values, adjusts calculated
> >> to admissible ranges, enlarges cycles if required and converts values
> >> into SMC's format.
> >>* Old driver calculates CS_SETUP and CS_PULSE cycles incorrectly
> >> because of wrong assumptions.
> >> New code calculates:
> >> CS_SETUP = SETUP/2
> >If you to this, then {RD,WR}_SETUP have to be equal SETUP + SETUP/2
> >to generate proper setup (t0) time on IDE bus. I think the best way is
err, setup time is t1

> >set CS_SETUP and CS_HOLD to 0 (what your code do if SETUP and HOLD<=1),
> >but to do this you need to take care of data float (t6z)
>
> Why so?
>
> This is not clear for me. Maybe we talk about different things or I
> have wrong
> understanding of ATA timings.
> Can you please look at "Standard Read Cycle" for AT91SAM9 MCU
> http://www.kicad.ru/files/AT91SAM9G20%20bus%20timing.pdf
> , CompactFlash connection schematic
> http://www.kicad.ru/files/CF%20for%20AT91SAM9%20(True%20IDE%20mode).pdf
> and comment my thoughts?
Full "External Bus Interface" section from AT91 spec is important,
because is describe how SMC works internally in CF True IDE mode.

> Here is a legend for "Standard Read Cycle" timing diagram.
> ------------------------------------------------------------------------------
> Read (NRD) signal parameters:
> * t0 = cycle = NRD_CYCLE
> * t1 = setup = NRD_SETUP
> * t2 = pulse = NRD_PULSE
> * t9 = hold = NRD_HOLD
Correct. Also t0 = t1 + t2 + t9 relation must be true.

> Chip Select (NCS) signal parameters:
> * cs_setup = NCS_RD_SETUP
> * cs_pulse = NCS_RD_PULSE
> * cs_cycle = cycle
You can setup that, but they need to have proper relations with NRD.

> Notes:
> * The NCS_RD_CYCLE is equal to the NRD_CYCLE for AT91SAM9, because they
> start/finish simultaneously (HW related).
No, NCS and NRD are different signals, waveforms are different (if configured
differently in SMC controller).
> * The NCS signal is not the same as CS1, CS2 ATA signals! It used only to
> enable data bus transceiver U2.
Well, they are different signals but connected together. All of these are
controlled by NCS: CFCE1 (CS1), CFCE2 (CS2), CFRNW (DIR), CFCS0 (OE)
if SMC is configured in True IDE mode.

Stanislaw


\
 
 \ /
  Last update: 2011-04-27 20:41    [from the cache]
©2003-2011 Jasper Spaans