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Explorer
Explorer
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Registered: ‎05-28-2014

mmc/sd - Is the clock determined by hdf or u-boot/linux?

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Hello,

 

I am not sure who is responsible for clock of mmc.

We have problem working with 50M (we get errors both in u-boot and linux), so we made a change in hdf and changed the clock to 10.101010M, now we manage to access from u-boot, but it still fails in linux.

 

I am therefore not sure how is that it started workin in u-boot after hdf reduced mmc clock modification.

If the cpu software (u-boot & linux) determines the mmc clock, then how is it that reducing the clock in hdf, made u-boot read/write starts working ?

I guess it started working because the hdf determines the real clock ? If yes - then why linux still fails , though u-boot works ?

 

 

 

 The u-boot test is simple:

mmc dev 0

mmc erase 0 1

mmc write 0x08010000 0 1 

 

mmc read 0x08000000 0 1

 

 

Regards,

Ran

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Explorer
Explorer
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Registered: ‎11-22-2015

the hdf doesn't not result in any changes in u-boot or linux kernel.  A change in the hdf would result in a new devicetree for the linux boot process.  The hdf does directly affect the FSBL but I can't say what the FSBL does for the SD clock.  From what you describe it sounds like the FSBL is changing it, u-boot does nothing and then the linux devicetree is changing again.

 

jeff

 

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Explorer
Explorer
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Registered: ‎11-22-2015

the hdf doesn't not result in any changes in u-boot or linux kernel.  A change in the hdf would result in a new devicetree for the linux boot process.  The hdf does directly affect the FSBL but I can't say what the FSBL does for the SD clock.  From what you describe it sounds like the FSBL is changing it, u-boot does nothing and then the linux devicetree is changing again.

 

jeff

 

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