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tx4938ide: Check minimum cycle time and SHWT range (v2)

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SHWT value is used as address valid to -CSx assertion and -CSx to -DIOx
assertion setup time, and contrarywise, -DIOx to -CSx release and -CSx
release to address invalid hold time, so it actualy applies 4 times and
so constitutes -DIOx recovery time.  Check requirement of the recovery
time and cycle time.  Also check SHWT maximum value.

Suggested-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: ralf@linux-mips.org
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
This commit is contained in:
Atsushi Nemoto 2008-11-02 21:40:09 +01:00 committed by Bartlomiej Zolnierkiewicz
parent ccd32e221c
commit 630a8b2500
1 changed files with 8 additions and 1 deletions
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9
drivers/ide/tx4938ide.c
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@ -39,10 +39,17 @@ static void tx4938ide_tune_ebusc(unsigned int ebus_ch,
/* Address-valid to DIOR/DIOW setup */
shwt = DIV_ROUND_UP(t->setup, cycle);
/* -DIOx recovery time (SHWT * 4) and cycle time requirement */
while ((shwt * 4 + wt + (wt ? 2 : 3)) * cycle < t->cycle)
shwt++;
if (shwt > 7) {
pr_warning("tx4938ide: SHWT violation (%d)\n", shwt);
shwt = 7;
}
pr_debug("tx4938ide: ebus %d, bus cycle %dns, WT %d, SHWT %d\n",
ebus_ch, cycle, wt, shwt);
__raw_writeq((cr & ~(0x3f007ull)) | (wt << 12) | shwt,
__raw_writeq((cr & ~0x3f007ull) | (wt << 12) | shwt,
&tx4938_ebuscptr->cr[ebus_ch]);
}