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Re: [PATCH v4 5/5] hw/nvram/eeprom_at24c: Make reset behavior more like
From: |
Corey Minyard |
Subject: |
Re: [PATCH v4 5/5] hw/nvram/eeprom_at24c: Make reset behavior more like hardware |
Date: |
Wed, 25 Jan 2023 15:41:30 -0600 |
On Tue, Jan 17, 2023 at 06:42:14PM -0800, Peter Delevoryas wrote:
> EEPROM's are a form of non-volatile memory. After power-cycling an EEPROM,
> I would expect the I2C state machine to be reset to default values, but I
> wouldn't really expect the memory to change at all.
Yes, I agree, I was actually wondering about this reviewing earlier
changes. Thanks for fixing this.
Reviewed-by: Corey Minyard <cminyard@mvista.com>
>
> The current implementation of the at24c EEPROM resets its internal memory on
> reset. This matches the specification in docs/devel/reset.rst:
>
> Cold reset is supported by every resettable object. In QEMU, it means we
> reset
> to the initial state corresponding to the start of QEMU; this might differ
> from what is a real hardware cold reset. It differs from other resets (like
> warm or bus resets) which may keep certain parts untouched.
>
> But differs from my intuition. For example, if someone writes some information
> to an EEPROM, then AC power cycles their board, they would expect the EEPROM
> to
> retain that information. It's very useful to be able to test things like this
> in QEMU as well, to verify software instrumentation like determining the cause
> of a reboot.
>
> Fixes: 5d8424dbd3e8 ("nvram: add AT24Cx i2c eeprom")
> Signed-off-by: Peter Delevoryas <peter@pjd.dev>
> Reviewed-by: Joel Stanley <joel@jms.id.au>
> ---
> hw/nvram/eeprom_at24c.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/hw/nvram/eeprom_at24c.c b/hw/nvram/eeprom_at24c.c
> index f8d751fa278d..5074776bff04 100644
> --- a/hw/nvram/eeprom_at24c.c
> +++ b/hw/nvram/eeprom_at24c.c
> @@ -185,18 +185,6 @@ static void at24c_eeprom_realize(DeviceState *dev, Error
> **errp)
> }
>
> ee->mem = g_malloc0(ee->rsize);
> -
> -}
> -
> -static
> -void at24c_eeprom_reset(DeviceState *state)
> -{
> - EEPROMState *ee = AT24C_EE(state);
> -
> - ee->changed = false;
> - ee->cur = 0;
> - ee->haveaddr = 0;
> -
> memset(ee->mem, 0, ee->rsize);
>
> if (ee->init_rom) {
> @@ -214,6 +202,16 @@ void at24c_eeprom_reset(DeviceState *state)
> }
> }
>
> +static
> +void at24c_eeprom_reset(DeviceState *state)
> +{
> + EEPROMState *ee = AT24C_EE(state);
> +
> + ee->changed = false;
> + ee->cur = 0;
> + ee->haveaddr = 0;
> +}
> +
> static Property at24c_eeprom_props[] = {
> DEFINE_PROP_UINT32("rom-size", EEPROMState, rsize, 0),
> DEFINE_PROP_BOOL("writable", EEPROMState, writable, true),
> --
> 2.39.0
>
>
- Re: [PATCH v4 3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper, (continued)
- Re: [PATCH v4 3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper, Peter Delevoryas, 2023/01/25
- Re: [PATCH v4 3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper, Cédric Le Goater, 2023/01/26
- RE: [PATCH v4 3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper, Ninad S Palsule, 2023/01/26
- Re: [PATCH v4 3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper, Cédric Le Goater, 2023/01/26
- RE: [PATCH v4 3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper, Ninad S Palsule, 2023/01/26
Re: [PATCH v4 3/5] hw/nvram/eeprom_at24c: Add init_rom field and at24c_eeprom_init_rom helper, Corey Minyard, 2023/01/25
[PATCH v4 5/5] hw/nvram/eeprom_at24c: Make reset behavior more like hardware, Peter Delevoryas, 2023/01/17
[PATCH v4 4/5] hw/arm/aspeed: Add aspeed_eeprom.c, Peter Delevoryas, 2023/01/17