On Mon, Dec 09, 2024, André Draszik wrote:
> Before writing a new value to the register, the old value needs to be
> masked out for the new value to be programmed as intended, because at
> least in some cases the reset value of that field is 0xf (max value).
>
> At the moment, the dwc3 core initialises the threshold to the maximum
> value (0xf), with the option to override it via a DT. No upstream DTs
> seem to override it, therefore this commit doesn't change behaviour for
> any upstream platform. Nevertheless, the code should be fixed to have
> the desired outcome.
>
> Do so.
>
> Fixes: 80caf7d21adc ("usb: dwc3: add lpm erratum support")
> Cc: stable@xxxxxxxxxxxxxxx # 5.10+ (needs adjustment for 5.4)
> Signed-off-by: André Draszik <andre.draszik@xxxxxxxxxx>
> ---
> Changes in v2:
> - change mask definitions to be consistent with other masks (Thinh)
> - udpate commit message to clarify that in some cases the reset value
> is != 0
> - Link to v1: https://urldefense.com/v3/__https://lore.kernel.org/r/20241206-dwc3-nyet-fix-v1-1-293bc74f644f@linaro.org__;!!A4F2R9G_pg!exwT5XPAys9S8l6RyyVaky6AnKD2swNq-bjYs5za6qQvktfSS812CHZGh-U6oPOu1rIuJ-tPe9TWIEsIHYnbbOmsRfr7$
> ---
> For stable-5.4, the if() test is slightly different, so a separate
> patch will be sent for it for the patch to apply.
> ---
> drivers/usb/dwc3/core.h | 1 +
> drivers/usb/dwc3/gadget.c | 4 +++-
> 2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index ee73789326bc..f11570c8ffd0 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -464,6 +464,7 @@
> #define DWC3_DCTL_TRGTULST_SS_INACT (DWC3_DCTL_TRGTULST(6))
>
> /* These apply for core versions 1.94a and later */
> +#define DWC3_DCTL_NYET_THRES_MASK (0xf << 20)
> #define DWC3_DCTL_NYET_THRES(n) (((n) & 0xf) << 20)
>
> #define DWC3_DCTL_KEEP_CONNECT BIT(19)
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 83dc7304d701..31a654c6f15b 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -4195,8 +4195,10 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
> WARN_ONCE(DWC3_VER_IS_PRIOR(DWC3, 240A) && dwc->has_lpm_erratum,
> "LPM Erratum not available on dwc3 revisions < 2.40a\n");
>
> - if (dwc->has_lpm_erratum && !DWC3_VER_IS_PRIOR(DWC3, 240A))
> + if (dwc->has_lpm_erratum && !DWC3_VER_IS_PRIOR(DWC3, 240A)) {
> + reg &= ~DWC3_DCTL_NYET_THRES_MASK;
> reg |= DWC3_DCTL_NYET_THRES(dwc->lpm_nyet_threshold);
> + }
>
> dwc3_gadget_dctl_write_safe(dwc, reg);
> } else {
>
> ---
> base-commit: c245a7a79602ccbee780c004c1e4abcda66aec32
> change-id: 20241206-dwc3-nyet-fix-7085f6d71d04
>
> Best regards,
> --
> André Draszik <andre.draszik@xxxxxxxxxx>
>
Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
Thanks,
Thinh
