Re: [PATCH 1/5] [RESEND][edk2-platforms] Silicon/SynQuacerI2cDxe: Wait for bus busy


Leif Lindholm
 

On Fri, Nov 05, 2021 at 18:23:28 +0900, Masami Hiramatsu wrote:
If an EFI application frequently repeats SetTime and GetTime,
the I2C bus can be busy and failed to start. To fix this issue,
add waiting loop for the bus busy status. (Usually, it is
enough to read 3 times for checking, but for safety this
sets 10 for timeout.)

This also clean up the code path a bit so that it is easy to
understand what should do on each combinations of BSR.BB and
BCR.MSS.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@...>
Reported-by: Kazuhiko Sakamoto <sakamoto.kazuhiko@...>
---
.../Drivers/SynQuacerI2cDxe/SynQuacerI2cDxe.c | 38 ++++++++++++++------
1 file changed, 26 insertions(+), 12 deletions(-)

diff --git a/Silicon/Socionext/SynQuacer/Drivers/SynQuacerI2cDxe/SynQuacerI2cDxe.c b/Silicon/Socionext/SynQuacer/Drivers/SynQuacerI2cDxe/SynQuacerI2cDxe.c
index 31f6e3072f..380eba8059 100644
--- a/Silicon/Socionext/SynQuacer/Drivers/SynQuacerI2cDxe/SynQuacerI2cDxe.c
+++ b/Silicon/Socionext/SynQuacer/Drivers/SynQuacerI2cDxe/SynQuacerI2cDxe.c
@@ -16,6 +16,8 @@
//
#define WAIT_FOR_INTERRUPT_TIMEOUT 50000

+#define WAIT_FOR_BUS_BUSY_TIMEOUT 10
+
I think it would be more clear English to say that we are waiting
_for_ the bus to be *ready* - meaning that we are waiting _while_ the
bus is *busy*.

So I suggest
WAIT_FOR_BUS_BUSY_TIMEOUT ->
WAIT_FOR_BUS_READY_TIMEOUT

/**
Set the frequency for the I2C clock line.

@@ -152,6 +154,7 @@ SynQuacerI2cMasterStart (
IN EFI_I2C_OPERATION *Op
)
{
+ UINTN Timeout = WAIT_FOR_BUS_BUSY_TIMEOUT;
This indentation does not match the subsequent lines.

/
Leif

UINT8 Bsr;
UINT8 Bcr;

@@ -167,24 +170,35 @@ SynQuacerI2cMasterStart (
Bsr = MmioRead8 (I2c->MmioBase + F_I2C_REG_BSR);
Bcr = MmioRead8 (I2c->MmioBase + F_I2C_REG_BCR);

- if ((Bsr & F_I2C_BSR_BB) && !(Bcr & F_I2C_BCR_MSS)) {
- DEBUG ((DEBUG_INFO, "%a: bus is busy\n", __FUNCTION__));
- return EFI_ALREADY_STARTED;
- }
+ if (!(Bcr & F_I2C_BCR_MSS)) {

- if (Bsr & F_I2C_BSR_BB) { // Bus is busy
- DEBUG ((DEBUG_INFO, "%a: Continuous Start\n", __FUNCTION__));
- MmioWrite8 (I2c->MmioBase + F_I2C_REG_BCR, Bcr | F_I2C_BCR_SCC);
- } else {
- if (Bcr & F_I2C_BCR_MSS) {
- DEBUG ((DEBUG_WARN,
- "%a: is not in master mode\n", __FUNCTION__));
- return EFI_DEVICE_ERROR;
+ if (Bsr & F_I2C_BSR_BB) { // Bus is busy
+ do {
+ Bsr = MmioRead8 (I2c->MmioBase + F_I2C_REG_BSR);
+ } while (Timeout-- && (Bsr & F_I2C_BSR_BB));
+
+ if (Bsr & F_I2C_BSR_BB) {
+ DEBUG ((DEBUG_INFO, "%a: bus is busy\n", __FUNCTION__));
+ return EFI_ALREADY_STARTED;
+ }
}
+
DEBUG ((DEBUG_INFO, "%a: Start Condition\n", __FUNCTION__));
MmioWrite8 (I2c->MmioBase + F_I2C_REG_BCR,
Bcr | F_I2C_BCR_MSS | F_I2C_BCR_INTE | F_I2C_BCR_BEIE);
+
+ } else { // F_I2C_BCR_MSS is set
+
+ if (!(Bsr & F_I2C_BSR_BB)) {
+ DEBUG ((DEBUG_WARN,
+ "%a: is not in master mode\n", __FUNCTION__));
+ return EFI_DEVICE_ERROR;
+ }
+
+ DEBUG ((DEBUG_INFO, "%a: Continuous Start\n", __FUNCTION__));
+ MmioWrite8 (I2c->MmioBase + F_I2C_REG_BCR, Bcr | F_I2C_BCR_SCC);
}
+
return EFI_SUCCESS;
}

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