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authorSergei Shtylyov <sshtylyov@ru.mvista.com>2007-03-17 16:57:24 -0400
committerBartlomiej Zolnierkiewicz <bzolnier@gmail.com>2007-03-17 16:57:24 -0400
commite277a1aaa97abdc1b0a0b8a8c062e29220b00440 (patch)
tree9ff0abc93858f4e519be55c2f594114000324961
parentcd05a1f818073a623455a58e756c5b419fc98db9 (diff)
cmd64x: fix recovery time calculation (take 3)
The driver wrongly takes the address setup time into account when calculating the PIO recovery time -- this leads to slight overclocking of the PIO modes 0 and 1 (so, the prayers failed to help, as usual :-). Rework the code to be calculating recovery clock count as a difference between the total cycle count and the active count (we don't need to calculate the recovery time itself since it's not specified for the PIO modes 0 to 2, and for modes 3 and 4 this formula gives enough recovery time anyway in the chip's supported PCI frequency range). This patch has been inspired by reading the datasheets and looking at what the libata driver does; it has been compile-tested only (as usual :-) but anyway, the new code gives the same or longer recovery times than the old one... Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com> Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
-rw-r--r--drivers/ide/pci/cmd64x.c45
1 files changed, 20 insertions, 25 deletions
diff --git a/drivers/ide/pci/cmd64x.c b/drivers/ide/pci/cmd64x.c
index b0d4825c56a9..561197f7b5bb 100644
--- a/drivers/ide/pci/cmd64x.c
+++ b/drivers/ide/pci/cmd64x.c
@@ -1,6 +1,6 @@
1/* $Id: cmd64x.c,v 1.21 2000/01/30 23:23:16 1/* $Id: cmd64x.c,v 1.21 2000/01/30 23:23:16
2 * 2 *
3 * linux/drivers/ide/pci/cmd64x.c Version 1.41 Feb 3, 2007 3 * linux/drivers/ide/pci/cmd64x.c Version 1.42 Feb 8, 2007
4 * 4 *
5 * cmd64x.c: Enable interrupts at initialization time on Ultra/PCI machines. 5 * cmd64x.c: Enable interrupts at initialization time on Ultra/PCI machines.
6 * Note, this driver is not used at all on other systems because 6 * Note, this driver is not used at all on other systems because
@@ -189,6 +189,11 @@ static int cmd64x_get_info (char *buffer, char **addr, off_t offset, int count)
189 189
190#endif /* defined(DISPLAY_CMD64X_TIMINGS) && defined(CONFIG_PROC_FS) */ 190#endif /* defined(DISPLAY_CMD64X_TIMINGS) && defined(CONFIG_PROC_FS) */
191 191
192static u8 quantize_timing(int timing, int quant)
193{
194 return (timing + quant - 1) / quant;
195}
196
192/* 197/*
193 * This routine writes the prepared setup/active/recovery counts 198 * This routine writes the prepared setup/active/recovery counts
194 * for a drive into the cmd646 chipset registers to active them. 199 * for a drive into the cmd646 chipset registers to active them.
@@ -268,47 +273,37 @@ static void program_drive_counts (ide_drive_t *drive, int setup_count, int activ
268 */ 273 */
269static u8 cmd64x_tune_pio (ide_drive_t *drive, u8 mode_wanted) 274static u8 cmd64x_tune_pio (ide_drive_t *drive, u8 mode_wanted)
270{ 275{
271 int setup_time, active_time, recovery_time; 276 int setup_time, active_time, cycle_time;
272 int clock_time, pio_mode, cycle_time; 277 u8 cycle_count, setup_count, active_count, recovery_count;
273 u8 recovery_count2, cycle_count; 278 u8 pio_mode;
274 int setup_count, active_count, recovery_count; 279 int clock_time = 1000 / system_bus_clock();
275 int bus_speed = system_bus_clock(); 280 ide_pio_data_t pio;
276 ide_pio_data_t d;
277 281
278 pio_mode = ide_get_best_pio_mode(drive, mode_wanted, 5, &d); 282 pio_mode = ide_get_best_pio_mode(drive, mode_wanted, 5, &pio);
279 cycle_time = d.cycle_time; 283 cycle_time = pio.cycle_time;
280 284
281 /*
282 * I copied all this complicated stuff from cmd640.c and made a few
283 * minor changes. For now I am just going to pray that it is correct.
284 */
285 setup_time = ide_pio_timings[pio_mode].setup_time; 285 setup_time = ide_pio_timings[pio_mode].setup_time;
286 active_time = ide_pio_timings[pio_mode].active_time; 286 active_time = ide_pio_timings[pio_mode].active_time;
287 recovery_time = cycle_time - (setup_time + active_time);
288 clock_time = 1000 / bus_speed;
289 cycle_count = (cycle_time + clock_time - 1) / clock_time;
290
291 setup_count = (setup_time + clock_time - 1) / clock_time;
292 287
293 active_count = (active_time + clock_time - 1) / clock_time; 288 setup_count = quantize_timing( setup_time, clock_time);
289 cycle_count = quantize_timing( cycle_time, clock_time);
290 active_count = quantize_timing(active_time, clock_time);
294 291
295 recovery_count = (recovery_time + clock_time - 1) / clock_time; 292 recovery_count = cycle_count - active_count;
296 recovery_count2 = cycle_count - (setup_count + active_count); 293 /* program_drive_counts() takes care of zero recovery cycles */
297 if (recovery_count2 > recovery_count)
298 recovery_count = recovery_count2;
299 if (recovery_count > 16) { 294 if (recovery_count > 16) {
300 active_count += recovery_count - 16; 295 active_count += recovery_count - 16;
301 recovery_count = 16; 296 recovery_count = 16;
302 } 297 }
303 if (active_count > 16) 298 if (active_count > 16)
304 active_count = 16; /* maximum allowed by cmd646 */ 299 active_count = 16; /* maximum allowed by cmd64x */
305 300
306 program_drive_counts (drive, setup_count, active_count, recovery_count); 301 program_drive_counts (drive, setup_count, active_count, recovery_count);
307 302
308 cmdprintk("%s: PIO mode wanted %d, selected %d (%dns)%s, " 303 cmdprintk("%s: PIO mode wanted %d, selected %d (%dns)%s, "
309 "clocks=%d/%d/%d\n", 304 "clocks=%d/%d/%d\n",
310 drive->name, mode_wanted, pio_mode, cycle_time, 305 drive->name, mode_wanted, pio_mode, cycle_time,
311 d.overridden ? " (overriding vendor mode)" : "", 306 pio.overridden ? " (overriding vendor mode)" : "",
312 setup_count, active_count, recovery_count); 307 setup_count, active_count, recovery_count);
313 308
314 return pio_mode; 309 return pio_mode;