Re: [Qemu-devel] [PATCH v2 5/9] hw/block/pflash_cfi01: Add the DeviceReset() handler

[John Snow <jsnow@redhat.com>]

On 7/1/19 8:12 PM, Philippe Mathieu-Daudé wrote:
> A "system reset" sets the device state machine in READ_ARRAY mode
> and, after some delay, set the SR.7 READY bit.
> 
> We do not model timings, so we set the SR.7 bit directly.
> 
> This pflash device is a child of TYPE_DEVICE.
> The TYPE_DEVICE interface provide a DeviceReset handler which will
> be called after the device is realized, and each time the machine
> resets itself.
> 
> To avoid incoherent states when the machine resets (see but report
> below), factor out the reset code into pflash_cfi01_system_reset,
> and register the method as a device reset callback.
> 
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1678713
> Reported-by: Laszlo Ersek <lersek@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>

Does reset always get called as part of realize, really?

Or are we just trusting that the device is probably going to get reset
by the guest during bringup?

> ---
>  hw/block/pflash_cfi01.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
> index dd1dfd266b..8d632ea941 100644
> --- a/hw/block/pflash_cfi01.c
> +++ b/hw/block/pflash_cfi01.c
> @@ -763,8 +763,6 @@ static void pflash_cfi01_realize(DeviceState *dev, Error **errp)
>          pfl->max_device_width = pfl->device_width;
>      }
>  
> -    pflash_mode_read_array(pfl);
> -    pfl->status = 0x80; /* WSM ready */
>      /* Hardcoded CFI table */
>      /* Standard "QRY" string */
>      pfl->cfi_table[0x10] = 'Q';
> @@ -852,6 +850,18 @@ static void pflash_cfi01_realize(DeviceState *dev, Error **errp)
>      pfl->cfi_table[0x3f] = 0x01; /* Number of protection fields */
>  }
>  
> +static void pflash_cfi01_system_reset(DeviceState *dev)
> +{
> +    PFlashCFI01 *pfl = PFLASH_CFI01(dev);
> +
> +    pflash_mode_read_array(pfl);
> +    /*
> +     * The WSM ready timer occurs at most 150ns after system reset.
> +     * This model deliberately ignores this delay.
> +     */
> +    pfl->status = 0x80;
> +}
> +
>  static Property pflash_cfi01_properties[] = {
>      DEFINE_PROP_DRIVE("drive", PFlashCFI01, blk),
>      /* num-blocks is the number of blocks actually visible to the guest,
> @@ -896,6 +906,7 @@ static void pflash_cfi01_class_init(ObjectClass *klass, void *data)
>  {
>      DeviceClass *dc = DEVICE_CLASS(klass);
>  
> +    dc->reset = pflash_cfi01_system_reset;
>      dc->realize = pflash_cfi01_realize;
>      dc->props = pflash_cfi01_properties;
>      dc->vmsd = &vmstate_pflash;
>