Re: [PATCH v6 2/3] hw/sd/sdhci: Support big endian SD host controller interfaces

[Guenter Roeck]

On Sat, Apr 29, 2023 at 01:46:26PM -0700, Guenter Roeck wrote:
> Hi,
> 
> On Tue, Nov 01, 2022 at 11:29:33PM +0100, Philippe Mathieu-Daudé wrote:
> > Some SDHCI IP can be synthetized in various endianness:
> > https://github.com/u-boot/u-boot/blob/v2021.04/doc/README.fsl-esdhc
> > 
> >  - CONFIG_SYS_FSL_ESDHC_BE
> > 
> >    ESDHC IP is in big-endian mode. Accessing ESDHC registers can be
> >    determined by ESDHC IP's endian mode or processor's endian mode.
> > 
> > Our current implementation is little-endian. In order to support
> > big endianness:
> > 
> > - Rename current MemoryRegionOps as sdhci_mmio_le_ops ('le')
> > - Add an 'endianness' property to SDHCIState (default little endian)
> > - Set the 'io_ops' field in realize() after checking the property
> > - Add the sdhci_mmio_be_ops (big-endian) MemoryRegionOps.
> > 
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> 
> With this patch in place (in qemu v8.0), I can no longer boot linux
> from SD card with sabrelite, mcimx6ul-evk, and mcimx7d-sabre emulations.
> I get the following persistent errors.
> 
> [   12.210101] sdhci-esdhc-imx 2194000.mmc: 
> esdhc_wait_for_card_clock_gate_off: card clock still not gate off in 100us!.
> [   12.213222] sdhci-esdhc-imx 2194000.mmc: 
> esdhc_wait_for_card_clock_gate_off: card clock still not gate off in 100us!.
> [   12.215072] sdhci-esdhc-imx 2194000.mmc: 
> esdhc_wait_for_card_clock_gate_off: card clock still not gate off in 100us!.
> [   12.218766] sdhci-esdhc-imx 2190000.mmc: 
> esdhc_wait_for_card_clock_gate_off: card clock still not gate off in 100us!.
> [   12.220441] sdhci-esdhc-imx 2190000.mmc: 
> esdhc_wait_for_card_clock_gate_off: card clock still not gate off in 100us!.
> [   12.221542] sdhci-esdhc-imx 2190000.mmc: 
> esdhc_wait_for_card_clock_gate_off: card clock still not gate off in 100us!.
> [   12.241544] sdhci-esdhc-imx 2190000.mmc: 
> esdhc_wait_for_card_clock_gate_off: card clock still not gate off in 100us!.
> [   12.242608] sdhci-esdhc-imx 2190000.mmc: card clock still not stable in 
> 100us!.
> 
> The emulations start to work again after reverting this patch.
> 
Cause explained below.

> Guenter
> 
> > ---
> >  hw/sd/sdhci-internal.h |  1 +
> >  hw/sd/sdhci.c          | 32 +++++++++++++++++++++++++++++---
> >  include/hw/sd/sdhci.h  |  1 +
> >  3 files changed, 31 insertions(+), 3 deletions(-)
> > 
> > diff --git a/hw/sd/sdhci-internal.h b/hw/sd/sdhci-internal.h
> > index 964570f8e8..5f3765f12d 100644
> > --- a/hw/sd/sdhci-internal.h
> > +++ b/hw/sd/sdhci-internal.h
> > @@ -308,6 +308,7 @@ extern const VMStateDescription sdhci_vmstate;
> >  #define SDHC_CAPAB_REG_DEFAULT 0x057834b4
> >  
> >  #define DEFINE_SDHCI_COMMON_PROPERTIES(_state) \
> > +    DEFINE_PROP_UINT8("endianness", _state, endianness, 
> > DEVICE_LITTLE_ENDIAN), \
> >      DEFINE_PROP_UINT8("sd-spec-version", _state, sd_spec_version, 2), \
> >      DEFINE_PROP_UINT8("uhs", _state, uhs_mode, UHS_NOT_SUPPORTED), \
> >      DEFINE_PROP_UINT8("vendor", _state, vendor, SDHCI_VENDOR_NONE), \
> > diff --git a/hw/sd/sdhci.c b/hw/sd/sdhci.c
> > index 22c758ad91..289baa879e 100644
> > --- a/hw/sd/sdhci.c
> > +++ b/hw/sd/sdhci.c
> > @@ -1329,7 +1329,7 @@ sdhci_write(void *opaque, hwaddr offset, uint64_t 
> > val, unsigned size)
> >                         value >> shift, value >> shift);
> >  }
> >  
> > -static const MemoryRegionOps sdhci_mmio_ops = {
> > +static const MemoryRegionOps sdhci_mmio_le_ops = {
> >      .read = sdhci_read,
> >      .write = sdhci_write,
> >      .impl = {
> > @@ -1344,6 +1344,21 @@ static const MemoryRegionOps sdhci_mmio_ops = {
> >      .endianness = DEVICE_LITTLE_ENDIAN,
> >  };
> >  
> > +static const MemoryRegionOps sdhci_mmio_be_ops = {
> > +    .read = sdhci_read,
> > +    .write = sdhci_write,
> > +    .impl = {
> > +        .min_access_size = 4,
> > +        .max_access_size = 4,
> > +    },
> > +    .valid = {
> > +        .min_access_size = 1,
> > +        .max_access_size = 4,
> > +        .unaligned = false
> > +    },
> > +    .endianness = DEVICE_BIG_ENDIAN,
> > +};
> > +
> >  static void sdhci_init_readonly_registers(SDHCIState *s, Error **errp)
> >  {
> >      ERRP_GUARD();
> > @@ -1371,8 +1386,6 @@ void sdhci_initfn(SDHCIState *s)
> >  
> >      s->insert_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, 
> > sdhci_raise_insertion_irq, s);
> >      s->transfer_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, 
> > sdhci_data_transfer, s);
> > -
> > -    s->io_ops = &sdhci_mmio_ops;

The reason for initializing io_ops here is that the same driver also
supports imx_usdhc. That function also sets io_ops to usdhc specific
io ops. This is now overwritten by ...

> >  }
> >  
> >  void sdhci_uninitfn(SDHCIState *s)
> > @@ -1388,10 +1401,23 @@ void sdhci_common_realize(SDHCIState *s, Error 
> > **errp)
> >  {
> >      ERRP_GUARD();
> >  
> > +    switch (s->endianness) {
> > +    case DEVICE_LITTLE_ENDIAN:
> > +        s->io_ops = &sdhci_mmio_le_ops;
> > +        break;
> > +    case DEVICE_BIG_ENDIAN:
> > +        s->io_ops = &sdhci_mmio_be_ops;
> > +        break;
> > +    default:
> > +        error_setg(errp, "Incorrect endianness");
> > +        return;
> > +    }
> > +

... this code which runs later and never sets usdhc_mmio_ops.
Consequently io_ops now points to the wrong ops functions for imx.

Guenter