Peter Kardos

Unknown delay during boot (i.mx253) when DMA is enabled.

Discussion created by Peter Kardos on Jan 26, 2012
Latest reply on Oct 29, 2012 by Fabio Estevam

Hi folks.

On your custom board based on i.mx253 running a stock 2.6.39.4 kernel, i've noticed a strange behavior when DMA is enabled.

For some reason the booting stalls for ~60s, and resumes without any error and/or warnings.

From what i could find out, the DMA in mx25 is the same as in mx35. I'm using a firmware originally designed for mx35 with the 2.6.39.4 kernel, "stock defaults" with the 3.x.x kernels.

I've tried different kernels; 3.0.8, 3.1.2, 3.2.0 all behaving the same way...

Is this a normal behavior? Am i doing something wrong, am i missing something?

Is there a way to improve the speed?

<snip>

[    3.386247] mousedev: PS/2 mouse device common for all mice
[    3.390370] input: gpio-keys as /devices/platform/gpio-keys/input/input0
[    3.397442] input: TSC2007 Touchscreen as /devices/virtual/input/input1
[    3.404424] rtc-ds1307 0-0068: SET TIME!
[    3.409180] rtc-ds1307 0-0068: rtc core: registered ds1339 as rtc0
[    3.413267] i2c /dev entries driver
[   64.181134] imx-sdma imx-sdma: initialized
[   64.184593] sdhci: Secure Digital Host Controller Interface driver
[   64.188044] sdhci: Copyright(c) Pierre Ossman
[   64.190758] _regulator_get: sdhci-esdhc-imx.1 supply vmmc not found, using dummy regulator
[   64.196746] mmc0: SDHCI controller on platform [sdhci-esdhc-imx.1] using DMA

</snip>

Thanx for your help in advance.

Cheers, Kardy

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