On 26.07.2018 15:56, Peter Geis wrote: > On 07/12/2018 03:39 AM, Stefan Agner wrote: >> It seems that SD3.0 advertisement needs to be set for higher eMMC >> speed modes (namely DDR52) as well. The TRM states that the SD3.0 >> advertisement bit should be set for all controller instances, even >> for those not supporting UHS-I mode... >> >> When specifying vqmmc-supply as a fixed 1.8V regulator on a Tegra >> SD/MMC instance which is connected to a eMMC device, the stack >> enables SD3.0. However, enabling it has consequences: If SDHCI 3.0 >> support is advertised the stack enables Auto-CMD23. Unfortunately >> Auto-CMD23 seems not to work well with Tegra 3 currently. It leads >> to regular warnings: >> mmc2: Got command interrupt 0x00010000 even though no command operation was in progress. >> >> It is not entirely clear why those errors happens. It seems that >> a Linux 3.1 based downstream kernel which has Auto-CMD23 support >> does not show those warnings. >> >> Use quirk SDHCI_QUIRK2_ACMD23_BROKEN to prevent Auto-CMD23 being >> used for now. With this the eMMC works stable on high-speed mode >> while still announcing SD3.0. >> >> This allows to use mmc-ddr-1_8v to enables DDR52 mode. In DDR52 >> mode read speed improves from about 42MiB/s to 72MiB/s on an >> Apalis T30. >> >> Signed-off-by: Stefan Agner <stefan@xxxxxxxx> >> --- >> drivers/mmc/host/sdhci-tegra.c | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c >> index 888a1ad511db..11c0b2069c7c 100644 >> --- a/drivers/mmc/host/sdhci-tegra.c >> +++ b/drivers/mmc/host/sdhci-tegra.c >> @@ -336,7 +336,15 @@ static const struct sdhci_pltfm_data sdhci_tegra30_pdata = { >> SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC | >> SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN, >> .quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN | >> - SDHCI_QUIRK2_BROKEN_HS200, >> + SDHCI_QUIRK2_BROKEN_HS200 | >> + /* >> + * Auto-CMD23 leads to "Got command interrupt 0x00010000 even >> + * though no command operation was in progress." >> + * >> + * The exact reason is unknown, as the same hardware seems >> + * to support Auto CMD23 on a downstream 3.1 kernel. >> + */ >> + SDHCI_QUIRK2_ACMD23_BROKEN, >> .ops = &tegra_sdhci_ops, >> }; >> > > I finally got around to testing this on the Ouya (Tegra 3). Thanks for testing! > > I found that the "Got command interrupt 0x00010000 even though no > command operation was in progress." error occurred when the interface > is unstable. > I've had a lot of problems with sdmmc4 stability on the Ouya above 34 > Mhz, probably due to the fact that they are using the internal cmd and > clock pull-up resistors, against the TRM's instruction. > At 39Mhz, I saw the error this patch corrects. > With the patch, the error went away, but the interface is still > unstable under load. How does this instability manifest exactly? > > Lowering down to 32Mhz, without the patch there are no errors. So the patch does not make it less stable right? -- Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html