> From: Christian König [mailto:deathsimple at vodafone.de] > Sent: Tuesday, January 24, 2017 10:09 PM > To: Xue, Ken; amd-gfx mailing list > Cc: dl.SRDC_SW_GPUVirtualization > Subject: Re: [PATCH] drm/amdgpu: Refine the handshake between guest and > server by mailbox > > Am 24.01.2017 um 13:55 schrieb Xue, Ken: > > Add check for bit RCV_MSG_VALID of MAILBOX_CONTROL before reading > > message and after ACK server. > > > > Change-Id: I717a77fd90dfbdfce4dc56e978338ffc5db24fca > > Signed-off-by: Ken Xue <Ken.Xue at amd.com> > > --- > > drivers/gpu/drm/amd/amdgpu/mxgpu_vi.c | 20 ++++++++++++++++++++ > > 1 file changed, 20 insertions(+) > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_vi.c > > b/drivers/gpu/drm/amd/amdgpu/mxgpu_vi.c > > index d2622b6..b2c46db 100644 > > --- a/drivers/gpu/drm/amd/amdgpu/mxgpu_vi.c > > +++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_vi.c > > @@ -318,10 +318,25 @@ void xgpu_vi_init_golden_registers(struct > amdgpu_device *adev) > > static void xgpu_vi_mailbox_send_ack(struct amdgpu_device *adev) > > { > > u32 reg; > > + int timeout = VI_MAILBOX_TIMEDOUT; > > + u32 mask = REG_FIELD_MASK(MAILBOX_CONTROL, RCV_MSG_VALID); > > > > reg = RREG32(mmMAILBOX_CONTROL); > > reg = REG_SET_FIELD(reg, MAILBOX_CONTROL, RCV_MSG_ACK, 1); > > WREG32(mmMAILBOX_CONTROL, reg); > > + > > + /*Wait for RCV_MSG_VALID to be 0*/ > > + reg = RREG32(mmMAILBOX_CONTROL); > > + while (reg & mask) { > > + if (timeout <= 0) { > > + pr_err("RCV_MSG_VALID is not cleared\n"); > > + break; > > + } > > + msleep(1); > > Are you sure that you want to use msleep() here instead of mdelay() ? > > msleep() is horrible inaccurate, e.g. depending on the definition of HZ you can > sleep for 10ms instead of 1ms IIRC. > > mdelay() is a busy wait, so the CPU can't do anything else useful while waiting > but I don't think that this will hurt us here. Thanks for your suggestion. Currently, msleep may be a correct choice. 1)accuracy is not necessary here 2)the VI_MAILBOX_TIMEDOUT is 5000. if there is an issue from server side, driver may be delayed 5 seconds 3)I followed the same style like other codes in the same file. Regards, Ken
