Subject: [Regression Resend] mmc: mx28: sd card detection broken since 3.18-rc1

From: [email-masked] (Kristina Martšenko)
Date: Mon, 03 Nov 2014 01:01:07 +0200

On 01/11/14 23:40, Stefan Wahren wrote:
> Hi,
> 
> i was testing Linux Kernel 3.18-rc2 with my i.MX28 board (I2SE Duckbill) and ran
> into the problem that the sd card isn't detected from the Kernel at booting
> (driver: mxs-mmc.c). That results in a endless wait for the root partition
> 
> Here are the relevant messages (bad case):
> 
> [...]
> [    1.501883] mxs-mmc 80010000.ssp: initialized
> [    1.521203] TCP: cubic registered
> [    1.530850] NET: Registered protocol family 10
> [    1.548469] mip6: Mobile IPv6
> [    1.551698] sit: IPv6 over IPv4 tunneling driver
> [    1.566016] ip6_gre: GRE over IPv6 tunneling driver
> [    1.575831] NET: Registered protocol family 17
> [    1.581640] bridge: automatic filtering via arp/ip/ip6tables has been
> deprecated. Update your scripts to load br_netfilter if you need this.
> [    1.595635] Key type dns_resolver registered
> [    1.604302] registered taskstats version 1
> [    1.618188] stmp3xxx-rtc 80056000.rtc: setting system clock to 1970-01-01
> 00:00:03 UTC (3)
> [    1.675580] Waiting for root device /dev/mmcblk0p3...
> 
> In Linux Kernel 3.17 that problem didn't exist (good case):
> 
> [...]
> [    1.546857] mxs-mmc 80010000.ssp: initialized
> [    1.576363] TCP: cubic registered
> [    1.588856] NET: Registered protocol family 10
> [    1.608208] mmc0: host does not support reading read-only switch. assuming
> write-enable.
> [    1.616927] mip6: Mobile IPv6
> [    1.620028] sit: IPv6 over IPv4 tunneling driver
> [    1.629900] mmc0: new high speed SDHC card at address 0007
> [    1.642901] ip6_gre: GRE over IPv6 tunneling driver
> [    1.652047] mmcblk0: mmc0:0007 SD16G 14.6 GiB
> [    1.662108] NET: Registered protocol family 17
> [    1.678091]  mmcblk0: p1 p2 p3
> [...]
> 
> I've have bisected the problem to this commit:
> 
> commit 89168b48991537bec2573b3b6a8841df74465b12
> Author: Linus Walleij <[email-masked]>
> Date:   Thu Oct 2 09:08:46 2014 +0200
> 
>     mmc: core: restore detect line inversion semantics
>    
>     commit 98e90de99a0c43bd434da814c882c4332441871e
>     "mmc: host: switch OF parser to use gpio descriptors"
>     switched the semantic behaviour of card detect and read
>     only flags such that the inversion capability flag would
>     only be set if inversion was explicitly specified in the
>     device tree, in the hopes that no-one was using double
>     inversion.
>    
>     It turns out that the XOR:ing between the explicit
>     inversion was indeed in use, so we need to restore the
>     old semantics where both ways of inversion are checked
>     and the end result XOR:ed.
>    
>     Reported-by: Javier Martinez Canillas <[email-masked]>
>     Tested-by: Javier Martinez Canillas <[email-masked]>
>     Signed-off-by: Linus Walleij <[email-masked]>
>     Signed-off-by: Ulf Hansson <[email-masked]>
> 
> Kernel command line: -e noinitrd console=ttyAMA0,115200 root=/dev/mmcblk0p3 rw
> rootwait
> 
> It looks to me that the patch didn't fix all host controller.

I ran into this issue as well. Seems that a card-detect flag 
(MMC_CAP2_CD_ACTIVE_HIGH) can currently be set based on an 
uninitialized variable, which can lead to the card being reported as 
not present. This patch fixes it for me:

diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 03c53b72a2d6..f0e187682d3b 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -311,7 +311,7 @@ int mmc_of_parse(struct mmc_host *host)
 	struct device_node *np;
 	u32 bus_width;
 	int len, ret;
-	bool cap_invert, gpio_invert;
+	bool cap_invert, gpio_invert = false;
 
 	if (!host->parent || !host->parent->of_node)
 		return 0;
@@ -401,6 +401,7 @@ int mmc_of_parse(struct mmc_host *host)
 	else
 		cap_invert = false;
 
+	gpio_invert = false;
 	ret = mmc_gpiod_request_ro(host, "wp", 0, false, 0, &gpio_invert);
 	if (ret) {
 		if (ret == -EPROBE_DEFER)

Let me know if this also fixes it for you, and I'll send in a proper 
patch.

Thanks,
Kristina