On 03/12/2013 12:05 PM, Tom Warren wrote:
Stephen,
On Tue, Mar 12, 2013 at 10:54 AM, Stephen Warren swarren@wwwdotorg.org wrote:
On 03/12/2013 10:17 AM, Tom Warren wrote:
T114 requires SD bus power-rail bringup for the SDIO card on SDMMC3.
diff --git a/board/nvidia/dalmore/dalmore.c b/board/nvidia/dalmore/dalmore.c
+void board_sdmmc_voltage_init(void)
/* TPS65913: LDO9_VOLTAGE = 3.3V */data_buffer[0] = 0x31;reg = 0x61;for (i = 0; i < MAX_I2C_RETRY; ++i) {ret = i2c_write(PMU_I2C_ADDRESS, reg, 1, data_buffer, 1);if (ret) {udelay(100);printf("%s: PMU i2c_write %02X<-%02X returned %d\n",__func__, reg, data_buffer[0], ret);}}Is there actually a need to retry these transactions; is there any evidence they're expected to fail? Hopefully the HW isn't flaky like that.
This is how it was done in the original internal U-Boot code I got the I2C writes from (also done this way on T30). I did add the printf error writes, though, when I was having a PWR_I2C/I2C5/dev 0 problem. I think Whistler does something similar.
Whistler doesn't do any retries. That's why I was surprised by this. I would assert we should remove the retry logic unless there's a specific need for it, in which case we need to port it to the kernel too.