Hi RobertCNelson,
I recently knew that the SD card was just one type of MMC, but I just made
a mistake. Thank you for your advice.
yes, I knew that the am335x MMCHS supports up to 4-bit mode on SD cards.
>PS, the factory default eMMC on these boards isn't known for speed,
>the version used is more for reliability.
The eMMC configured in bbb may be doing a good job in terms of price, but
...
>You can buy pretty cheap fast microSD on a 4-bit bus that will outpace
>the factory default eMMC on a 8-bit bus..
I didn't really think that the types and manufacture of SD cards and MMCs
could affect the transfer speed so much.
regards,
2021年2月23日火曜日 11:40:46 UTC+9 RobertCNelson:
> On Mon, Feb 22, 2021 at 8:34 PM ha ppay <ando...@gmail.com> wrote:
> >
> > Hi RobertCNelson,
> >
> > Thank you for checking the relevant part.
> > the description of the Device tree is as follows. Is this overwriting
> the setting? In fact, when I set this part to
> > bus-width = <0x08>
> > , the Boot time did not change much.
> > Could you tell me if there is a way to check the current transfer bit
> mode?
> >
> >
> > mmc@48060000 {
> > compatible = "ti,omap4-hsmmc";
> > ti,hwmods = "mmc1";
> > ti,dual-volt;
> > ti,needs-special-reset;
> > ti,needs-special-hs-handling;
> > dmas = < 0x2d 0x18 0x00 0x00 0x2d 0x19 0x00 0x00 >;
> > dma-names = "tx\0rx";
> > interrupts = < 0x40 >;
> > reg = < 0x48060000 0x1000 >;
> > status = "okay";
> > bus-width = < 0x04 >; <=======
> > pinctrl-names = "default";
> > pinctrl-0 = < 0x2e >;
> > cd-gpios = < 0x2f 0x06 0x01 >;
> > vmmc-supply = < 0x30 >;
> > phandle = < 0x288 >;
> > };
>
> Well, mmc@48060000 -> is the microSD on the BBBW -> which only has 4
> data wires hooked up...
>
> So, yeah, that won't change the eMMC..
>
> PS, the factory default eMMC on these boards isn't known for speed,
> the version used is more for reliability..
>
> You can buy pretty cheap fast microSD on a 4-bit bus that will outpace
> the factory default eMMC on a 8-bit bus..
>
> Regards,
>
> --
> Robert Nelson
> https://rcn-ee.com/
>
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