From fd5e62e22db29a067d3f26ba54caac308eb5e3a8 Mon Sep 17 00:00:00 2001 From: Sergei Shtylyov Date: Mon, 7 Dec 2009 23:38:11 +0400 Subject: pata_hpt{37x|3x2n}: improve timing register documentation Describe UDMA timing bits 18-20 and 21 separately; add a note to bit 31 about it being meaningful for PIO only. Reformat the whole comment, while at it... Signed-off-by: Sergei Shtylyov Signed-off-by: Jeff Garzik --- drivers/ata/pata_hpt37x.c | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) (limited to 'drivers/ata/pata_hpt37x.c') diff --git a/drivers/ata/pata_hpt37x.c b/drivers/ata/pata_hpt37x.c index 9b191763e6e..228dc1a8992 100644 --- a/drivers/ata/pata_hpt37x.c +++ b/drivers/ata/pata_hpt37x.c @@ -39,25 +39,24 @@ struct hpt_chip { /* key for bus clock timings * bit - * 0:3 data_high_time. inactive time of DIOW_/DIOR_ for PIO and MW - * DMA. cycles = value + 1 - * 4:8 data_low_time. active time of DIOW_/DIOR_ for PIO and MW - * DMA. cycles = value + 1 - * 9:12 cmd_high_time. inactive time of DIOW_/DIOR_ during task file + * 0:3 data_high_time. Inactive time of DIOW_/DIOR_ for PIO and MW DMA. + * cycles = value + 1 + * 4:8 data_low_time. Active time of DIOW_/DIOR_ for PIO and MW DMA. + * cycles = value + 1 + * 9:12 cmd_high_time. Inactive time of DIOW_/DIOR_ during task file * register access. - * 13:17 cmd_low_time. active time of DIOW_/DIOR_ during task file + * 13:17 cmd_low_time. Active time of DIOW_/DIOR_ during task file * register access. - * 18:21 udma_cycle_time. clock freq and clock cycles for UDMA xfer. - * during task file register access. - * 22:24 pre_high_time. time to initialize 1st cycle for PIO and MW DMA - * xfer. - * 25:27 cmd_pre_high_time. time to initialize 1st PIO cycle for task + * 18:20 udma_cycle_time. Clock cycles for UDMA xfer. + * 21 CLK frequency for UDMA: 0=ATA clock, 1=dual ATA clock. + * 22:24 pre_high_time. Time to initialize 1st cycle for PIO and MW DMA xfer. + * 25:27 cmd_pre_high_time. Time to initialize 1st PIO cycle for task file * register access. - * 28 UDMA enable - * 29 DMA enable - * 30 PIO_MST enable. if set, the chip is in bus master mode during - * PIO. - * 31 FIFO enable. + * 28 UDMA enable. + * 29 DMA enable. + * 30 PIO_MST enable. If set, the chip is in bus master mode during + * PIO xfer. + * 31 FIFO enable. Only for PIO. */ static struct hpt_clock hpt37x_timings_33[] = { -- cgit v1.2.3