On Thu, Jun 23, 2022 at 03:53:41PM +0200, Ulf Hansson wrote:
> On Thu, 23 Jun 2022 at 10:00, Vincent Whitchurch
> <vincent.whitchurch@xxxxxxxx> wrote:
> > During board verification, there is a need to test the various supported
> > eMMC/SD speed modes. However, since the framework chooses the best mode
> > supported by the card and the host controller's caps, this currently
> > necessitates changing the devicetree for every iteration.
> >
> > To make changing the modes easier, allow the various host controller
> > capabilities to be cleared via a module parameter. (A per-controller
> > debugfs wouldn't work since the controller needs to be re-probed to
> > trigger re-init of cards. A module parameter is used instead of a
>
> I think we could make use of a per-controller debugfs thing, if used
> in combination with MMC_CAP_AGGRESSIVE_PM and runtime PM.
>
> As runtime PM also has sysfs interface for each device, we can control
> runtime PM for the card's device (to trigger re-initialization of the
> card). In between runtime suspend/resume of the card's device, we
> should be able to change the supported speed modes, through debug fs.
>
> Would this work for you?
I got it to work with the below commands and the following patch. Note
that:
(1) MMC_CAP_AGGRESSIVE_PM also needs to be turned on via debugfs to
avoid having to patch the kernel. The cap is checked on every call
to runtime_suspend so it (currently) works to set it without
re-probing the host.
(2) I had to call mmc_select_card_type() even if there is an old card
since currently it's only called from mmc_decode_ext_csd().
Also, unlike the module parameter, this can't be set from bootargs, but
that part is not important for my use case.
root@(none):/sys/kernel/debug/mmc0# grep timing ios
timing spec: 9 (mmc HS200)
// Turn on MMC_CAP_AGGRESSIVE_PM and re-trigger runtime suspend
root@(none):/sys/kernel/debug/mmc0# echo $(($(cat caps) | (1 << 7))) > caps
root@(none):/sys/kernel/debug/mmc0# echo on > /sys/bus/mmc/devices/mmc0\:0001/power/control
root@(none):/sys/kernel/debug/mmc0# echo auto > /sys/bus/mmc/devices/mmc0\:0001/power/control
// MMC_CAP2_HS200_1_8V_SDR
root@(none):/sys/kernel/debug/mmc0# echo $(($(cat caps2) & ~(1 << 5))) > caps2
root@(none):/sys/kernel/debug/mmc0# echo on > /sys/bus/mmc/devices/mmc0\:0001/power/control
root@(none):/sys/kernel/debug/mmc0# grep timing ios
timing spec: 8 (mmc DDR52)
8<----
diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
index 3fdbc801e64a..721925300611 100644
--- a/drivers/mmc/core/debugfs.c
+++ b/drivers/mmc/core/debugfs.c
@@ -12,9 +12,12 @@
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/fault-inject.h>
+#include <linux/time.h>
#include <linux/mmc/card.h>
#include <linux/mmc/host.h>
+#include <linux/mmc/mmc.h>
+#include <linux/mmc/sd.h>
#include "core.h"
#include "card.h"
@@ -223,6 +226,47 @@ static int mmc_clock_opt_set(void *data, u64 val)
DEFINE_DEBUGFS_ATTRIBUTE(mmc_clock_fops, mmc_clock_opt_get, mmc_clock_opt_set,
"%llu\n");
+static int mmc_caps_get(void *data, u64 *val)
+{
+ *val = *(u32 *)data;
+ return 0;
+}
+
+static int mmc_caps_set(void *data, u64 val)
+{
+ u32 *caps = data;
+ u32 diff = *caps ^ val;
+ u32 allowed = MMC_CAP_AGGRESSIVE_PM |
+ MMC_CAP_SD_HIGHSPEED |
+ MMC_CAP_MMC_HIGHSPEED |
+ MMC_CAP_UHS |
+ MMC_CAP_DDR;
+
+ if (diff & ~allowed)
+ return -EINVAL;
+
+ *caps = val;
+
+ return 0;
+}
+
+static int mmc_caps2_set(void *data, u64 val)
+{
+ u32 *caps = data;
+ u32 diff = *caps ^ val;
+ u32 allowed = MMC_CAP2_HSX00_1_8V | MMC_CAP2_HSX00_1_2V;
+
+ if (diff & ~allowed)
+ return -EINVAL;
+
+ *caps = val;
+
+ return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(mmc_caps_fops, mmc_caps_get, mmc_caps_set, "0x%08llx\n");
+DEFINE_DEBUGFS_ATTRIBUTE(mmc_caps2_fops, mmc_caps_get, mmc_caps2_set, "0x%08llx\n");
+
void mmc_add_host_debugfs(struct mmc_host *host)
{
struct dentry *root;
@@ -231,8 +275,10 @@ void mmc_add_host_debugfs(struct mmc_host *host)
host->debugfs_root = root;
debugfs_create_file("ios", S_IRUSR, root, host, &mmc_ios_fops);
- debugfs_create_x32("caps", S_IRUSR, root, &host->caps);
- debugfs_create_x32("caps2", S_IRUSR, root, &host->caps2);
+ debugfs_create_file("caps", S_IRUSR | S_IWUSR, root, &host->caps,
+ &mmc_caps_fops);
+ debugfs_create_file("caps2", S_IRUSR | S_IWUSR, root, &host->caps2,
+ &mmc_caps2_fops);
debugfs_create_file_unsafe("clock", S_IRUSR | S_IWUSR, root, host,
&mmc_clock_fops);
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 89cd48fcec79..c79c26add3da 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -1730,7 +1730,8 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
/* Erase size depends on CSD and Extended CSD */
mmc_set_erase_size(card);
- }
+ } else
+ mmc_select_card_type(card);
/* Enable ERASE_GRP_DEF. This bit is lost after a reset or power off. */
if (card->ext_csd.rev >= 3) {
