On 11/30/2020 3:14 PM, Bjorn Andersson wrote:
On Mon 30 Nov 16:51 CST 2020, Asutosh Das (asd) wrote:
On 11/30/2020 1:16 AM, Stanley Chu wrote:
UFS specficication allows different VCC configurations for UFS devices,
for example,
(1). 2.70V - 3.60V (By default)
(2). 1.70V - 1.95V (Activated if "vcc-supply-1p8" is declared in
device tree)
(3). 2.40V - 2.70V (Supported since UFS 3.x)
With the introduction of UFS 3.x products, an issue is happening that
UFS driver will use wrong "min_uV/max_uV" configuration to toggle VCC
regulator on UFU 3.x products with VCC configuration (3) used.
To solve this issue, we simply remove pre-defined initial VCC voltage
values in UFS driver with below reasons,
1. UFS specifications do not define how to detect the VCC configuration
supported by attached device.
2. Device tree already supports standard regulator properties.
Therefore VCC voltage shall be defined correctly in device tree, and
shall not be changed by UFS driver. What UFS driver needs to do is simply
enabling or disabling the VCC regulator only.
This is a RFC conceptional patch. Please help review this and feel
free to feedback any ideas. Once this concept is accepted, and then
I would post a more completed patch series to fix this issue.
Signed-off-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
---
drivers/scsi/ufs/ufshcd-pltfrm.c | 10 +---------
1 file changed, 1 insertion(+), 9 deletions(-)
diff --git a/drivers/scsi/ufs/ufshcd-pltfrm.c b/drivers/scsi/ufs/ufshcd-pltfrm.c
index a6f76399b3ae..3965be03c136 100644
--- a/drivers/scsi/ufs/ufshcd-pltfrm.c
+++ b/drivers/scsi/ufs/ufshcd-pltfrm.c
@@ -133,15 +133,7 @@ static int ufshcd_populate_vreg(struct device *dev, const char *name,
vreg->max_uA = 0;
}
- if (!strcmp(name, "vcc")) {
- if (of_property_read_bool(np, "vcc-supply-1p8")) {
- vreg->min_uV = UFS_VREG_VCC_1P8_MIN_UV;
- vreg->max_uV = UFS_VREG_VCC_1P8_MAX_UV;
- } else {
- vreg->min_uV = UFS_VREG_VCC_MIN_UV;
- vreg->max_uV = UFS_VREG_VCC_MAX_UV;
- }
- } else if (!strcmp(name, "vccq")) {
+ if (!strcmp(name, "vccq")) {
vreg->min_uV = UFS_VREG_VCCQ_MIN_UV;
vreg->max_uV = UFS_VREG_VCCQ_MAX_UV;
} else if (!strcmp(name, "vccq2")) {
Hi Stanley
Thanks for the patch. Bao (nguyenb) was also working towards something
similar.
Would it be possible for you to take into account the scenario in which the
same platform supports both 2.x and 3.x UFS devices?
These've different voltage requirements, 2.4v-3.6v.
I'm not sure if standard dts regulator properties can support this.
What is the actual voltage requirement for these devices and how does
the software know what voltage to pick in this range?
Regards,
Bjorn
-asd
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
Linux Foundation Collaborative Project
For platforms that support both 2.x (2.7v-3.6v) and 3.x (2.4v-2.7v), the
voltage requirements (Vcc) are 2.4v-3.6v. The software initializes the
ufs device at 2.95v & reads the version and if the device is 3.x, it may
do the following:
- Set the device power mode to SLEEP
- Disable the Vcc
- Enable the Vcc and set it to 2.5v
- Set the device power mode to ACTIVE
All of the above may be done at HS-G1 & moved to max supported gear
based on the device version, perhaps?
Am open to other ideas though.
-asd
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
Linux Foundation Collaborative Project
