On Mon 30 Nov 03:16 CST 2020, 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>
Reviewed-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
This is the correct thing to do and I would prefer that we did the same
for vccq and vccq2 as well - and thereby remove the min_uV and max_uV
from ufs_vreg.
Regards,
Bjorn
> ---
> 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")) {
> --
> 2.18.0
>
