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RE: [PATCH v2 1/1] hw/block/m25p80: Fix Numonyx fast read dummy cycle co
From: |
Joe Komlodi |
Subject: |
RE: [PATCH v2 1/1] hw/block/m25p80: Fix Numonyx fast read dummy cycle count |
Date: |
Wed, 28 Oct 2020 23:15:18 +0000 |
Hi Philippe,
Comments marked inline with [Joe]
-----Original Message-----
From: Philippe Mathieu-Daudé <philippe.mathieu.daude@gmail.com> On Behalf Of
Philippe Mathieu-Daudé
Sent: Wednesday, October 28, 2020 2:27 AM
To: Joe Komlodi <komlodi@xilinx.com>; qemu-devel@nongnu.org
Cc: Francisco Eduardo Iglesias <figlesia@xilinx.com>; kwolf@redhat.com;
alistair@alistair23.me; qemu-block@nongnu.org; mreitz@redhat.com
Subject: Re: [PATCH v2 1/1] hw/block/m25p80: Fix Numonyx fast read dummy cycle
count
Hi Joe,
On 10/28/20 12:43 AM, Joe Komlodi wrote:
> Numonyx chips determine the number of cycles to wait based on bits 7:4
> in the volatile configuration register.
>
> However, if these bits are 0x0 or 0xF, the number of dummy cycles to
> wait is
> 10 on a QIOR or QIOR4 command, or 8 on any other currently supported
> fast read command. [1]
>
> [1]
> https://www.micron.com/-/media/client/global/documents/products/data-s
> heet/ nor-flash/serial-nor/mt25q/die-rev-b/mt25q_qlkt_u_02g_cbb_0.pdf
> ?rev=9b167fbf2b3645efba6385949a72e453
Please use single line for URL (even longer than 80 characters):
https://www.micron.com/-/media/client/global/documents/products/data-sheet/nor-flash/serial-nor/mt25q/die-rev-b/mt25q_qlkt_u_02g_cbb_0.pdf
Or use
Datasheet: "MT25QU02GCBB Rev. H 05/19 EN"
[Joe] Ah, sorry about that, I'll put it all on one line in v3.
> Page 34, page 39 note 5
The note 5 is not restricted to QIOR/QIOR4 commands, so your patch seems
incomplete.
[Joe] Right. Right now it's only checking QIOR/QIOR4 because we don't have a
way to put Numonyx chips in QIO mode (s->quad_enable == true), and we don't
model DDR commands.
Because of those restrictions, all the read commands need 8 cycles, except for
QIOR/QIOR4.
>
> Signed-off-by: Joe Komlodi <komlodi@xilinx.com>
> ---
> hw/block/m25p80.c | 26 +++++++++++++++++++++++---
> 1 file changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/hw/block/m25p80.c b/hw/block/m25p80.c index
> 483925f..302ed9d 100644
> --- a/hw/block/m25p80.c
> +++ b/hw/block/m25p80.c
> @@ -820,6 +820,26 @@ static void reset_memory(Flash *s)
> trace_m25p80_reset_done(s);
> }
>
> +static uint8_t numonyx_extract_cfg_num_dummies(Flash *s) {
> + uint8_t cycle_count;
> + uint8_t num_dummies;
> + assert(get_man(s) == MAN_NUMONYX);
> +
> + cycle_count = extract32(s->volatile_cfg, 4, 4);
Could be easier to review as:
num_dummies = extract32(s->volatile_cfg, 4, 4);
switch (s->cmd_in_progress) {
/* note 5 comment ... */
case FAST_READ:
case ...
/* field erased or reset in NVRAM */
if (cycle_count == 0x0 || cycle_count == 0xf) {
switch (s->cmd_in_progress) {
case FAST_READ:
case ...:
num_dummies = 10;
break;
case ...:
case ...:
/* assert(s->quad_enable); */
num_dummies = 8;
break;
default:
qemu_log_mask(GUEST_ERROR, ...);
break;
}
}
break;
default:
break;
}
return num_dummies;
> + if (cycle_count == 0x0 || cycle_count == 0x0F) {
> + if (s->cmd_in_progress == QIOR || s->cmd_in_progress == QIOR4) {
> + num_dummies = 10;
> + } else {
> + num_dummies = 8;
Note, this is only true if s->quad_enable.
Maybe clever to use the dumbest approach and copy the table...
static uint8_t numonyx_extract_cfg_num_dummies(Flash *s) {
static const unsigned dummy_clock_cycles[0x100][3] = {
[FAST_READ] = {8, 8, 10},
...
};
uint8_t num_dummies = extract32(s->volatile_cfg, 4, 4);
if (cycle_count == 0x0 || cycle_count == 0xf) {
num_dummies = dummy_clock_cycles[s->cmd_in_progress][mode];
}
return num_dummies;
}
[Joe] I think either this or the switch statement would work fine, it just
depends if we want to add a way to set s->quad_enable and s->dual_enable
(doesn't exist in the model) for Numonyx chips.
To be the most accurate, it probably would be best to add a way to
enable/disable QIO and DIO mode for Numonyx chips, then change the cycles
needed accordingly.
Let me know what you think.
Thanks!
Joe
> + }
> + } else {
> + num_dummies = cycle_count;
> + }
> +
> + return num_dummies;
> +}
> +
> static void decode_fast_read_cmd(Flash *s) {
> s->needed_bytes = get_addr_length(s); @@ -829,7 +849,7 @@ static
> void decode_fast_read_cmd(Flash *s)
> s->needed_bytes += 8;
> break;
> case MAN_NUMONYX:
> - s->needed_bytes += extract32(s->volatile_cfg, 4, 4);
> + s->needed_bytes += numonyx_extract_cfg_num_dummies(s);
> break;
> case MAN_MACRONIX:
> if (extract32(s->volatile_cfg, 6, 2) == 1) { @@ -868,7 +888,7
> @@ static void decode_dio_read_cmd(Flash *s)
> );
> break;
> case MAN_NUMONYX:
> - s->needed_bytes += extract32(s->volatile_cfg, 4, 4);
> + s->needed_bytes += numonyx_extract_cfg_num_dummies(s);
> break;
> case MAN_MACRONIX:
> switch (extract32(s->volatile_cfg, 6, 2)) { @@ -908,7 +928,7
> @@ static void decode_qio_read_cmd(Flash *s)
> );
> break;
> case MAN_NUMONYX:
> - s->needed_bytes += extract32(s->volatile_cfg, 4, 4);
> + s->needed_bytes += numonyx_extract_cfg_num_dummies(s);
> break;
> case MAN_MACRONIX:
> switch (extract32(s->volatile_cfg, 6, 2)) {
>