On Wed, 2015-08-26 at 02:49 -0500, Lu Yangbo-B47093 wrote:

quoted

quoted

quoted

quoted

quoted

For T4240-R1.0-R2.0, the HOSTVER register has incorrcet vender
version value and sdhc spec version value. This will break down
the ADMA data transfer. So add workaround to get right value
VVN=0x13, SVN = 0x1.

So T4240-R1.0-R2.0 is the version of the controller, right?

If I understand correct you are checking what CPU/SoC you are
running on, to figure out which controller version you are using,
as that can't be fetched (trusted) from the registers of the esdhc
controller itself!?

Instead, you could deal with this directly in the DTS files. I
assume you have some DTS file for each SoC/board variant, right?

No, we do not have a separate DTS file for each revision of an SoC
-- and if we did, we'd constantly have people using the wrong one.

quoted

In principle, in your DTS file specific for the board/SoC that
holds the T4240-R1.0-R2.0 version of the controller, should add a
specific esdhc DT property to indicate this errata.

No, because (in addition to the above issue about chip revisions)
the device tree is stable ABI and errata are often discovered after
device trees are deployed.

Fair enough. Then what is your suggestion for the solution here?

As I said in my comment on patch 2/3, read SVR from the device-
config/guts MMIO block, which works on both PPC and ARM.

-Scott

Thanks, Scott.
I checked the device nodes of device-config/guts, finding all the platforms 
has not a uniform compatible name.
Could I add a compatible name called "fsl, dcfg"("fsl, guts" if using guts) 
for PowerPC P series, T series, B series boards, so that I could get this 
device node by compatible without knowing platform? 

No.  It's too vague.  Linux should keep a list of all the nodes it can match 
against for this.  Centralize it in one place rather than having each driver 
that cares about SVR do it.

-Scott