2016-03-24 17:22 GMT+01:00 Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>: > On Thu, Mar 24, 2016 at 09:06:45AM -0700, Doug Anderson wrote: >> Russell, > ... >> Presumably this is similar to what you saw: the host saw the CRC error >> but the card knew nothing about it. Sending the stop command during >> this time confused the card. Presumably the card was in transfer >> state during this time? > > If the card was in transfer state for a command which expects a stop > command, and that stop command was issued after the card entered > the transfer state, then I'd expect the card to handle it... though > there's always the firmware bug issue. > > If the card hadn't entered transfer state at the time the stop command > was issued.. I think that's more likely to hit card firmware issues. > > With the tuning commands, there's another case you can hit though: > the data transfer may have completed before you get around to sending > the stop command. > > That's why, for sdhci, I came to the conclusion that waiting for the > data transfer to complete or timeout was the best solution for SDHCI. > In fact I only saw the problem with dw_mmc-exynos, on dw_mmc-rockchip it doesn't happen because it enables the DW_MCI_QUIRK_BROKEN_DTO behaviour. What does this is use a kernel timer to signal when DTO interrupt does NOT come. Note that if I disable this quirk I can also saw the problem on rockchip. > Maybe, if sending a STOP command does cause card firmware issues, then: > > 1) it provides evidence that trying to send a stop command on response > CRC error is the wrong thing to do (it was talked about making SDHCI > do this.) > Seems the same here, so guess is the wrong thing to do. > 2) it suggests that the solution I came up with for SDHCI is the better > solution, rather than trying to immediately recover the situation by > sending a STOP command. > I'm wondering if just enable this quirk on exynos too is the proper solution. Unfortunately I don't have enough documentation to check differences between those controllers. Also will really help have access to some hardware that uses dw_mmc-pltfm to check if, like on exynos, same issue is triggered. Anyone with the hardware who can do some tests? > Maybe dw-mmc can do something similar, but with the lack of data transfer > timeout, maybe it's possible to do something with a kernel timer instead, > and check what the hardware is doing after a response CRC error? > > -- > RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ > FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up > according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
