Hi, On Friday 27 March 2015 12:44:03 Dong Aisheng wrote: > On Fri, Mar 27, 2015 at 11:52:04AM +0100, Juergen Borleis wrote: > > DMA and the required overhead on very small data blocks seems an > > expensive operation. Due to erratum ENGCM07207 for i.MX25 and i.MX35 SoCs > > the support for multiblock transfers is disabled which results into a > > huge amount of single 512 byte sector transfers and interrupts. This > > slows down the transmission speed to below 500 kiB/s (even at 50 MHz SD > > card clock). Using PIO instead of DMA to avoid ENGCM07207 happens and > > re-enabling multiblock transfers again improve the transmission > > capability up to about 2.5 MiB/s. > > > > I'm still not sure if ENGCM07207 is related to DMA only and can not > > happen when PIO is used instead. Someone out there with experience > > regarding this topic? > > The errata does not state it's related to DMA only. > http://cache.freescale.com/files/dsp/doc/errata/IMX35CE.pdf > I could double check with our IC guys to confirm it. Gentle ping. Regards, Juergen -- Pengutronix e.K. | Juergen Borleis | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
