Messages in this thread | | | Subject | Re: [PATCH] mmc: tegra: Disable UHS-I modes for tegra30 | From | Jon Hunter <> | Date | Tue, 10 May 2016 18:16:08 +0100 |
| |
On 10/05/16 17:34, Stephen Warren wrote: > On 05/10/2016 10:13 AM, Jon Hunter wrote:
[snip]
>> Stephen, for your u-boot testing, do you are set the bit in the vendor >> misc register to enable version 3.0 support for sdhci on tegra30? This >> is what the above quirk is doing (and has done so for a very long time). > > I don't see anything in the U-Boot driver that is equivalent to the > kernel's NVQUIRK_ENABLE_SDHCI_SPEC_300. I assume that means the > controller advertises an early spec version when in U-Boot, which simply > means U-Boot doesn't know to take advantage of any faster transfer modes > enabled by later specification versions, but I'm not entirely sure what > effect the following kernel code has on the HW: > >> /* Erratum: Enable SDHCI spec v3.00 support */ >> if (soc_data->nvquirks & NVQUIRK_ENABLE_SDHCI_SPEC_300) >> misc_ctrl |= SDHCI_MISC_CTRL_ENABLE_SDHCI_SPEC_300;
Do you see it touch the SDHCI_TEGRA_VENDOR_MISC_CTRL register?
The TRM states ...
"SDMMC_SPARE0[4] : When set, SD3.0 support is advertised in SDMMC_SLOT_INTERRUPT_STATUS_0_SPECIFICATION_VERSION_NUMBER Otherwise, only SD2.0 support is advertised"
So I *believe* this means that the sdhci version will now appear as 3.0 and so the host->version == SDHCI_SPEC_300. There are many places in the sdhci driver where it is checking ...
if (host->version >= SDHCI_SPEC_300) ...
> Perhaps the kernel driver should pulse the controller's CAR reset signal > in probe() to ensure that the HW is in a known state?
I will take a look.
Jon
| |