Heyi,
1) A couple ways to measure.
a) Loop calling gBS->Stall() and counting number of stall calls between
2 periodic timer event notifications. The accuracy of the measurement
depends on the granularity and accuracy of the Stall service. For your
use case, using a Stall() period between 10 uS and 100 uS should work
well.
b) Use the EFI_TIMESTAMP_PROTOCOL to get a performance counter value in
2 successive timer event notifications and use GetProperties() to convert
performance counter ticks to time. This protocol should provide more
accurate information, but it is optional, so the code that detects the
tick period has to check to see if this protocol is present and can use
it if it is present, and fall back to Stall() if it is not present.
2) I agree. Ignore time to first notification. Measure time between 2nd and
3rd notification.
3,4) I agree that setting TriggerTime to 0 makes the most sense.
Mike
> -----Original Message-----
> From: Heyi Guo [mailto:[email protected]]
> Sent: Wednesday, April 27, 2016 8:21 AM
> To: Kinney, Michael D <[email protected]>; [email protected]
> Cc: Tian, Feng <[email protected]>; Zeng, Star <[email protected]>
> Subject: Re: [edk2] [PATCH] MdeModulePkg/TerminalDxe: Set polling rate by
> serial IO
> mode
>
> Hi Michael,
>
> I still have questions about measuring timer tick by event:
>
> 1. How can we measure the time elapsed? TimerLib is not in UEFI spec,
> and shall we use gBS->Stall in a loop to measure the time?
> 2. By using a periodic timer event, I think we need to drop the 1st
> trigger as it is random and determined by the time when event is
> created, isn't it?
> 3. For the timer event with period of 1*100ns, I think it might be
> triggered twice in one timer tick by below code:
> Timer.c, line #143:
> Event->Timer.TriggerTime = Event->Timer.TriggerTime +
> Event->Timer.Period;
>
> //
> // If that's before now, then reset the timer to start from now
> //
> if (Event->Timer.TriggerTime <= SystemTime) {
> Event->Timer.TriggerTime = SystemTime;
> CoreSignalEvent (mEfiCheckTimerEvent);
> }
> 4. How about setting TriggerTime=0 when calling SetTimer so that the
> period of event will be exactly the timer tick, as stated in UEFI spec?
>
> Thanks and regards.
>
> Heyi
>
>
> On 04/27/2016 12:21 AM, Kinney, Michael D wrote:
> > Heyi,
> >
> > I agree the source code required to detect the current tick rate using only
> > UEFI
> services
> > is more complex.
> >
> > However, a UEFI driver (especially ones on an add-in devices such as a PCI
> > adapter)
> should not
> > use a PCD for the system tick rate because the add-in card can be used in
> > systems
> with different
> > system tick rates.
> >
> > If you are concerned about complexity, we could consider adding a new lib
> > function to
> the
> > UefiLib that returns the current system tick rate using UEFI services to
> > detect it.
> This way,
> > A UEFI driver can be kept simple and we move the complexity into a single
> > new lib
> function.
> >
> > Best regards,
> >
> > Mike
> >
> >> -----Original Message-----
> >> From: edk2-devel [mailto:[email protected]] On Behalf Of
> >> Heyi Guo
> >> Sent: Tuesday, April 26, 2016 8:14 AM
> >> To: Kinney, Michael D <[email protected]>; [email protected]
> >> Cc: Tian, Feng <[email protected]>; Zeng, Star <[email protected]>
> >> Subject: Re: [edk2] [PATCH] MdeModulePkg/TerminalDxe: Set polling rate by
> >> serial IO
> >> mode
> >>
> >> Hi Michael,
> >>
> >> It seems we are making the implementation more and more complicated. How
> >> about just creating a PCD for polling rate which can be set freely by
> >> platforms?
> >>
> >> Regards.
> >>
> >> Heyi
> >>
> >> On 04/24/2016 12:11 AM, Kinney, Michael D wrote:
> >>> Heyi Guo,
> >>>
> >>> The TerminalDxe driver is intended to be a UEFI Driver. The Timer Arch
> >>> Protocol is
> >>> a PI Protocol that is intended to be used by the PI DXE Core. In order to
> determine
> >>> the timer rate in a UEFI way, create a periodic timer event with a period
> >>> of 1,
> 100ns
> >>> unit, and then measure the time between timer event notification
> >>> functions.
> >>>
> >>> Mike
> >>>
> >>>> -----Original Message-----
> >>>> From: Heyi Guo [mailto:[email protected]]
> >>>> Sent: Saturday, April 23, 2016 1:54 AM
> >>>> To: [email protected]
> >>>> Cc: Heyi Guo <[email protected]>; Tian, Feng <[email protected]>;
> >>>> Zeng, Star
> >>>> <[email protected]>; Kinney, Michael D <[email protected]>
> >>>> Subject: [edk2] [PATCH] MdeModulePkg/TerminalDxe: Set polling rate by
> >>>> serial IO
> mode
> >>>>
> >>>> Calculate serial input polling rate according to parameters from
> >>>> serial IO mode as below, to fix potential input truncation.
> >>>>
> >>>> Polling interval (100ns) =
> >>>> FifoDepth * (StartBit + DataBits + StopBits + ParityBits) * 10,000,000
> >>>> / BaudRate
> >>>> (StopBits is assumed to be 1 and ParityBits is ignored for simplicity.
> >>>>
> >>>> However, as the event is time sensitive, we need to align the interval
> >>>> to timer interrupt period to make sure the event will be triggered at
> >>>> the expected rate. E.g. if the interval is 2.7ms and timer interrupt
> >>>> period is 1ms, the event will be triggered by time slice sequence as
> >>>> below:
> >>>> 3ms 3ms 2ms 3ms 3ms 2ms...
> >>>>
> >>>> In such case we will adjust the polling interval to be 2ms.
> >>>>
> >>>> Contributed-under: TianoCore Contribution Agreement 1.0
> >>>> Signed-off-by: Heyi Guo <[email protected]>
> >>>> Cc: Feng Tian <[email protected]>
> >>>> Cc: Star Zeng <[email protected]>
> >>>> Cc: Michael D Kinney <[email protected]>
> >>>> ---
> >>>> .../Universal/Console/TerminalDxe/Terminal.c | 5 +-
> >>>> .../Universal/Console/TerminalDxe/Terminal.h | 28 ++++++-
> >>>> .../Universal/Console/TerminalDxe/TerminalConIn.c | 92
> >>>> ++++++++++++++++++++++
> >>>> .../Universal/Console/TerminalDxe/TerminalDxe.inf | 1 +
> >>>> 4 files changed, 123 insertions(+), 3 deletions(-)
> >>>>
> >>>> diff --git a/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.c
> >>>> b/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.c
> >>>> index 6fde3b2..2944707 100644
> >>>> --- a/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.c
> >>>> +++ b/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.c
> >>>> @@ -71,6 +71,7 @@ TERMINAL_DEV mTerminalDevTemplate = {
> >>>> },
> >>>> NULL, // TerminalConsoleModeData
> >>>> 0, // SerialInTimeOut
> >>>> + 0, // KeyboardTimerInterval
> >>>>
> >>>> NULL, // RawFifo
> >>>> NULL, // UnicodeFiFo
> >>>> @@ -984,10 +985,12 @@ TerminalDriverBindingStart (
> >>>> );
> >>>> ASSERT_EFI_ERROR (Status);
> >>>>
> >>>> + TerminalDevice->KeyboardTimerInterval = GetKeyboardTimerInterval
> >>>> (Mode);
> >>>> +
> >>>> Status = gBS->SetTimer (
> >>>> TerminalDevice->TimerEvent,
> >>>> TimerPeriodic,
> >>>> - KEYBOARD_TIMER_INTERVAL
> >>>> + TerminalDevice->KeyboardTimerInterval
> >>>> );
> >>>> ASSERT_EFI_ERROR (Status);
> >>>>
> >>>> diff --git a/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h
> >>>> b/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h
> >>>> index 269d2ae..a1ff595 100644
> >>>> --- a/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h
> >>>> +++ b/MdeModulePkg/Universal/Console/TerminalDxe/Terminal.h
> >>>> @@ -28,6 +28,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND,
> >>>> EITHER
> EXPRESS
> >>>> OR IMPLIED.
> >>>> #include <Protocol/DevicePath.h>
> >>>> #include <Protocol/SimpleTextIn.h>
> >>>> #include <Protocol/SimpleTextInEx.h>
> >>>> +#include <Protocol/Timer.h>
> >>>>
> >>>> #include <Library/DebugLib.h>
> >>>> #include <Library/UefiDriverEntryPoint.h>
> >>>> @@ -68,8 +69,6 @@ typedef struct {
> >>>> UINTN Rows;
> >>>> } TERMINAL_CONSOLE_MODE_DATA;
> >>>>
> >>>> -#define KEYBOARD_TIMER_INTERVAL 200000 // 0.02s
> >>>> -
> >>>> #define TERMINAL_DEV_SIGNATURE SIGNATURE_32 ('t', 'm', 'n', 'l')
> >>>>
> >>>> #define TERMINAL_CONSOLE_IN_EX_NOTIFY_SIGNATURE SIGNATURE_32 ('t',
> >>>> 'm', 'e',
> 'n')
> >>>> @@ -91,6 +90,7 @@ typedef struct {
> >>>> EFI_SIMPLE_TEXT_OUTPUT_MODE SimpleTextOutputMode;
> >>>> TERMINAL_CONSOLE_MODE_DATA *TerminalConsoleModeData;
> >>>> UINTN SerialInTimeOut;
> >>>> + UINT64 KeyboardTimerInterval;
> >>>> RAW_DATA_FIFO *RawFiFo;
> >>>> UNICODE_FIFO *UnicodeFiFo;
> >>>> EFI_KEY_FIFO *EfiKeyFiFo;
> >>>> @@ -1358,4 +1358,28 @@ TerminalConInTimerHandler (
> >>>> IN EFI_EVENT Event,
> >>>> IN VOID *Context
> >>>> );
> >>>> +
> >>>> +/**
> >>>> + Calculate input polling timer interval by serial IO mode.
> >>>> +
> >>>> + @param Mode Pointer to serial IO mode.
> >>>> +
> >>>> + @retval The required polling timer interval in 100ns.
> >>>> +
> >>>> +**/
> >>>> +UINT64
> >>>> +GetKeyboardTimerInterval (
> >>>> + IN EFI_SERIAL_IO_MODE *Mode
> >>>> + );
> >>>> +
> >>>> +/**
> >>>> + Update period of polling timer event.
> >>>> +
> >>>> + @param TerminalDevice The terminal device to update.
> >>>> +**/
> >>>> +VOID
> >>>> +UpdatePollingRate (
> >>>> + IN TERMINAL_DEV *TerminalDevice
> >>>> + );
> >>>> +
> >>>> #endif
> >>>> diff --git a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c
> >>>> b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c
> >>>> index 3be877b..e7788a0 100644
> >>>> --- a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c
> >>>> +++ b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c
> >>>> @@ -15,6 +15,7 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND,
> >>>> EITHER
> EXPRESS
> >>>> OR IMPLIED.
> >>>>
> >>>> #include "Terminal.h"
> >>>>
> >>>> +EFI_TIMER_ARCH_PROTOCOL *gTimer;
> >>>>
> >>>> /**
> >>>> Reads the next keystroke from the input device. The WaitForKey
> >>>> Event can
> >>>> @@ -502,6 +503,94 @@ TerminalConInWaitForKey (
> >>>> }
> >>>>
> >>>> /**
> >>>> + Calculate input polling timer interval by serial IO mode.
> >>>> +
> >>>> + @param Mode Pointer to serial IO mode.
> >>>> +
> >>>> + @retval The required polling timer interval in 100ns.
> >>>> +
> >>>> +**/
> >>>> +UINT64
> >>>> +GetKeyboardTimerInterval (
> >>>> + IN EFI_SERIAL_IO_MODE *Mode
> >>>> + )
> >>>> +{
> >>>> + UINT32 FifoDepth;
> >>>> + UINT64 BaudRate;
> >>>> + UINT64 Interval;
> >>>> + UINT64 TimerPeriod;
> >>>> + EFI_STATUS Status;
> >>>> +
> >>>> + // Make some assumption if the values are not suitable for
> >>>> calculating.
> >>>> + BaudRate = Mode->BaudRate;
> >>>> + if (BaudRate == 0) {
> >>>> + BaudRate = 115200;
> >>>> + }
> >>>> + FifoDepth = Mode->ReceiveFifoDepth;
> >>>> + if (FifoDepth == 0) {
> >>>> + FifoDepth = 1;
> >>>> + }
> >>>> +
> >>>> + // We assume stop bits to be 1 and ignore parity bit to make it simple
> >>>> + // and fast enough to poll.
> >>>> + Interval = DivU64x64Remainder (
> >>>> + FifoDepth * (1 + Mode->DataBits + 1) * 10000000,
> >>>> + Mode->BaudRate,
> >>>> + NULL
> >>>> + );
> >>>> +
> >>>> + // As this is a time sensitive event, we still need to align the
> >>>> + // interval to timer interrupt period.
> >>>> + if (gTimer == NULL) {
> >>>> + Status = gBS->LocateProtocol (
> >>>> + &gEfiTimerArchProtocolGuid,
> >>>> + EFI_NATIVE_INTERFACE,
> >>>> + (VOID **) &gTimer
> >>>> + );
> >>>> + ASSERT_EFI_ERROR (Status);
> >>>> + }
> >>>> +
> >>>> + Status = gTimer->GetTimerPeriod (gTimer, &TimerPeriod);
> >>>> + ASSERT_EFI_ERROR (Status);
> >>>> +
> >>>> + if (Interval <= TimerPeriod) {
> >>>> + return TimerPeriod;
> >>>> + }
> >>>> + return MultU64x64 (DivU64x64Remainder (Interval, TimerPeriod, NULL),
> >> TimerPeriod);
> >>>> +}
> >>>> +
> >>>> +
> >>>> +/**
> >>>> + Update period of polling timer event.
> >>>> +
> >>>> + @param TerminalDevice The terminal device to update.
> >>>> +**/
> >>>> +VOID
> >>>> +UpdatePollingRate (
> >>>> + IN TERMINAL_DEV *TerminalDevice
> >>>> + )
> >>>> +{
> >>>> + UINT64 NewInterval;
> >>>> + EFI_STATUS Status;
> >>>> +
> >>>> + NewInterval = GetKeyboardTimerInterval
> >>>> (TerminalDevice->SerialIo->Mode);
> >>>> +
> >>>> + if (TerminalDevice->KeyboardTimerInterval == NewInterval) {
> >>>> + return;
> >>>> + }
> >>>> +
> >>>> + Status = gBS->SetTimer (
> >>>> + TerminalDevice->TimerEvent,
> >>>> + TimerPeriodic,
> >>>> + NewInterval
> >>>> + );
> >>>> + ASSERT_EFI_ERROR (Status);
> >>>> +
> >>>> + TerminalDevice->KeyboardTimerInterval = NewInterval;
> >>>> +}
> >>>> +
> >>>> +
> >>>> +/**
> >>>> Timer handler to poll the key from serial.
> >>>>
> >>>> @param Event Indicates the event that invoke
> >>>> this
> function.
> >>>> @@ -560,6 +649,9 @@ TerminalConInTimerHandler (
> >>>> TerminalDevice->SerialInTimeOut = SerialInTimeOut;
> >>>> }
> >>>> }
> >>>> +
> >>>> + UpdatePollingRate (TerminalDevice);
> >>>> +
> >>>> //
> >>>> // Check whether serial buffer is empty.
> >>>> // Skip the key transfer loop only if the SerialIo protocol instance
> >>>> diff --git a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalDxe.inf
> >>>> b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalDxe.inf
> >>>> index 0780296..dfd5035 100644
> >>>> --- a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalDxe.inf
> >>>> +++ b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalDxe.inf
> >>>> @@ -84,6 +84,7 @@
> >>>> gEfiSimpleTextInProtocolGuid ## BY_START
> >>>> gEfiSimpleTextInputExProtocolGuid ## BY_START
> >>>> gEfiSimpleTextOutProtocolGuid ## BY_START
> >>>> + gEfiTimerArchProtocolGuid ## CONSUMES
> >>>>
> >>>> [Pcd]
> >>>> gEfiMdePkgTokenSpaceGuid.PcdDefaultTerminalType ##
> SOMETIMES_CONSUMES
> >>>> --
> >>>> 2.7.0
> >> _______________________________________________
> >> edk2-devel mailing list
> >> [email protected]
> >> https://lists.01.org/mailman/listinfo/edk2-devel
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