[U-Boot] [PATCH V4 10/11] fsl_esdhc: add support for mx51 processor

[Stefano Babic]

Lv Terry-R65388 wrote:
> Hi Stefano,
> 

Hi Terry,

> Have you tested mmc on mx51 board?

Yes, of course. The whole patchset for mx51evk was tested on two
different releases of the board, with respectively a TO2 and a TO3
processor.

And the driver was tested with both MMC slots on the mx51evk (both are
supported):

For example, on a release 3.0 board:
U-Boot 2009.11-00347-g0b1898d (Feb 24 2010 - 11:30:10)

CPU:   Freescale i.MX51 family 3.0V at 800 MHz
Board: MX51EVK 3.0 [POR]

I get:
MMC:   FSL_ESDHC: 0, FSL_ESDHC: 1

MX51EVK U-Boot > mmcinfo
Device: FSL_ESDHC
Manufacturer ID: 1
OEM: 5041
Name: SP02G
Tran Speed: 25000000
Rd Block Len: 512
SD version 1.10
High Capacity: No
Capacity: 2014838784
Bus Width: 4-bit

MX51EVK U-Boot > fatls mmc 0
    14154   6091733.pdf

Of course, I have tested booting Linux that is stored on MMC, too.

> The original esdhc uses PIO mode in function esdhc_send_cmd(), while
> fsl_esdhc uses DMA mode.

I do not understand what you mean. I have not changed the type in
esdhc_xfertyp in my patch, it was already set to XFERTYP_DMAEN. The main
changes are related to set the correct accessors functions and these are
the only changes in esdhc_send_cmd().

> 
> I hasn't tested DMA mode before.

Have you tested this patch and have you found some issues ?

> BTW: have you considered add the feature to save environment data to
> mmc?

Adding the environment to the MMC is a feature that should be
implemented in a separate patch, because it is not strictly related to
the mx51evk. If it works, it must be possible to use it with all targets
having a MMC on board.

And I didn't want to add so much features before the patchset goes to
the mainline. I prefer that at least the basic support for a MX51
processor is in the mainline, allowing for others to add easier custom
boards with this SOC.

I think that such feature should be previously discussed on the ML.
On one side, it looks strange that the environment resides on a
removable media. On the other side, I understand that for test purposes
or for boards without other storage media this is a way to store it.

Regards,
Stefano

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