Re: [Qemu-devel] [PATCH v3 5/9] hw/block/pflash_cfi01: Add the DeviceReset() handler

[Alistair Francis]

On Fri, Jul 5, 2019 at 8:51 AM Philippe Mathieu-Daudé <address@hidden> 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.
>
> The TYPE_DEVICE interface provides a DeviceReset handler.
> This pflash device is a subclass of TYPE_SYS_BUS_DEVICE (which
> is a subclass of TYPE_DEVICE).
> SYS_BUS devices are automatically plugged into the 'main system
> bus', which is the root of the qbus tree.
> Devices in the qbus tree are guaranteed to have their reset()
> handler called after realize() and before we try to run the guest.
>
> 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 <address@hidden>
> Reviewed-by: John Snow <address@hidden>
> Regression-tested-by: Laszlo Ersek <address@hidden>
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>

Reviewed-by: Alistair Francis <address@hidden>

Alistair

> ---
> v3: reword description
> ---
>  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 200bfd0ab8..c32c67d01d 100644
> --- a/hw/block/pflash_cfi01.c
> +++ b/hw/block/pflash_cfi01.c
> @@ -762,8 +762,6 @@ 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';
> @@ -851,6 +849,18 @@ 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,
> @@ -895,6 +905,7 @@ 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;
> --
> 2.20.1
>
>