On Thu, 5 Sep 2019 at 22:01, Tim Schumacher <tim@xxxxxxxxxx> wrote: > > Hi, > > I'm sending this old bug by mail since a lot of developers don't use > bugzilla. > > Original bug report on bugzilla by Pedro Rodrigues from 2019-01-30: > > https://bugzilla.kernel.org/show_bug.cgi?id=202459 > > > This bug can be found on a Lenovo Miix 320-10ICR > > > > When using a SDXC (UHS) card, the screen becomes black if > > _mmc_sd_resume() is called. After some investigation, I found that an > > UHS card uses 1.8 V for signalling while a normal SD card uses 3.3 V. By > > forcing the SDXC to use 3.3 V the black screen does not appear. It seems > > that during a _mmc_sd_resume function call, while claiming the host, an > > I2C resume function is called based on an existing supplier link between > > the I2C bus and the card device. The problem is that if the signalling > > voltage is configured to 1.8 V, during the I2C resume call, the screen > > turns black. I was able to fix this issue by setting the initial signal > > voltage (3.3 V) before suspending the card, so that when the card is > > resumed, the voltage is in the original state. To do this I added a > > function call to mmc_set_initial_signal_voltage() during mmc_power_off > > routine (drivers/mmc/core/core.c). As I’m not an expert on Linux, I’m > > posting the issue and possible solution so that it could be implemented > > on a future release. > > > > Please, share your thoughts :) > > I can't provide further insight but I'm interested if this is possibly > the cause for the general issues people are having with the SD card > reader on Lenovo Miix 320 devices. > > Those issues described in posts like > > https://vincent-ventures.com/2018/12/arch-linux-on-lenovo-ideapad-miix-320/ > https://esc.sh/blog/linux-on-lenovo-miix-320/ > > are (1) black screen when booting with an SD card installed and (2) when > inserting an SD card after booting it shows up but upon trying to access > it the screen turns black until the card is removed again. > > I can confirm (1) on my Lenovo Miix 320-10ICR with kernel version > 5.2.11. I can also confirm that only SDXC cards are affected, SD and > SDHC cards work as expected. For the mmc community to help, you need to provide some kernel logs, output from lspci, figure out what mmc host driver that is being used, etc - in general collect more data. Then re-post the data to linux-mmc, me and a potential mmc host driver maintainer (if there is one). Yes, we can look into bugzilla as well, but first we need some more overall info in an email. Most likely, if there is any response, you will be asked to test patches. So you need to be able build and boot a new kernel, but I guess you already know that part. Kind regards Uffe
