Messages in this thread | | | Date | Tue, 27 Sep 2016 12:31:00 +0300 | From | Jarkko Sakkinen <> | Subject | Re: [PATCH v3 2/4] tmp/tpm_crb: fix Intel PTT hw bug during idle state |
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On Thu, Sep 15, 2016 at 09:23:29AM +0300, Jarkko Sakkinen wrote: > On Mon, Sep 12, 2016 at 04:04:19PM +0300, Tomas Winkler wrote: > > There is a HW bug in Skylake, and Broxton PCH Intel PTT device, where > > most of the registers in the control area except START, REQUEST, CANCEL, > > and LOC_CTRL lost retention when the device is in the idle state. Hence > > we need to bring the device to ready state before accessing the other > > registers. The fix brings device to ready state before trying to read > > command and response buffer addresses in order to remap the for access. > > > > Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> > > Tested-by: Jarkko Sakkinen <jarkko.sakkinn@linux.intel.com> > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinn@linux.intel.com>
I noticed something odd or at least not described in the commit message.
> /Jarkko > > > --- > > V2: cmd read need to be called also before crb_init as this will run > > self test. > > V3: resend. > > > > drivers/char/tpm/tpm_crb.c | 47 ++++++++++++++++++++++++++++++++++++++-------- > > 1 file changed, 39 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c > > index b6923a8b3ff7..e945177cf2c8 100644 > > --- a/drivers/char/tpm/tpm_crb.c > > +++ b/drivers/char/tpm/tpm_crb.c > > @@ -318,6 +318,7 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv, > > struct list_head resources; > > struct resource io_res; > > struct device *dev = &device->dev; > > + u32 pa_high, pa_low; > > u64 cmd_pa; > > u32 cmd_size; > > u64 rsp_pa; > > @@ -345,12 +346,27 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv, > > if (IS_ERR(priv->cca)) > > return PTR_ERR(priv->cca); > > > > - cmd_pa = ((u64) ioread32(&priv->cca->cmd_pa_high) << 32) | > > - (u64) ioread32(&priv->cca->cmd_pa_low); > > + /* > > + * PTT HW bug w/a: wake up the device to access > > + * possibly not retained registers. > > + */ > > + ret = crb_cmd_ready(dev, priv); > > + if (ret) > > + return ret; > > + > > + pa_high = ioread32(&priv->cca->cmd_pa_high); > > + pa_low = ioread32(&priv->cca->cmd_pa_low); > > + cmd_pa = ((u64)pa_high << 32) | pa_low; > > cmd_size = ioread32(&priv->cca->cmd_size); > > + > > + dev_dbg(dev, "cmd_hi = %X cmd_low = %X cmd_size %X\n", > > + pa_high, pa_low, cmd_size); > > + > > priv->cmd = crb_map_res(dev, priv, &io_res, cmd_pa, cmd_size); > > - if (IS_ERR(priv->cmd)) > > - return PTR_ERR(priv->cmd); > > + if (IS_ERR(priv->cmd)) { > > + ret = PTR_ERR(priv->cmd); > > + goto out; > > + } > > > > memcpy_fromio(&rsp_pa, &priv->cca->rsp_pa, 8); > > rsp_pa = le64_to_cpu(rsp_pa); > > @@ -358,7 +374,8 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv, > > > > if (cmd_pa != rsp_pa) { > > priv->rsp = crb_map_res(dev, priv, &io_res, rsp_pa, rsp_size); > > - return PTR_ERR_OR_ZERO(priv->rsp); > > + ret = PTR_ERR_OR_ZERO(priv->rsp); > > + goto out; > > } > > > > /* According to the PTP specification, overlapping command and response > > @@ -366,12 +383,18 @@ static int crb_map_io(struct acpi_device *device, struct crb_priv *priv, > > */ > > if (cmd_size != rsp_size) { > > dev_err(dev, FW_BUG "overlapping command and response buffer sizes are not identical"); > > - return -EINVAL; > > + ret = -EINVAL; > > + goto out; > > } > > + > > priv->cmd_size = cmd_size; > > > > priv->rsp = priv->cmd; > > - return 0; > > + > > +out: > > + crb_go_idle(dev, priv); > > + > > + return ret; > > } > > > > static int crb_acpi_add(struct acpi_device *device) > > @@ -415,7 +438,15 @@ static int crb_acpi_add(struct acpi_device *device) > > if (rc) > > return rc; > > > > - return crb_init(device, priv); > > + rc = crb_cmd_ready(dev, priv); > > + if (rc) > > + return rc;
You do this already in crb_map_io() that is called before crb_init(). What is the purpose of this extra crb_cmd_ready()? Looks unrelated at least to the described workaround.
> > + > > + rc = crb_init(device, priv); > > + if (rc) > > + crb_go_idle(dev, priv); > > + > > + return rc; > > } > > > > static int crb_acpi_remove(struct acpi_device *device) > > -- > > 2.7.4
/Jarkko
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