Re: [PATCH] usb: dwc3: core: enable CCI support

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Mon, Nov 06, 2023, Mehta, Piyush wrote:
> Hi Thinh,
> 
> > -----Original Message-----
> > From: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
> > Sent: Saturday, October 21, 2023 4:46 AM
> > To: Mehta, Piyush <piyush.mehta@amd.com>
> > Cc: gregkh@linuxfoundation.org; Simek, Michal <michal.simek@amd.com>;
> > Thinh Nguyen <Thinh.Nguyen@synopsys.com>; linux-usb@vger.kernel.org;
> > linux-kernel@vger.kernel.org; git (AMD-Xilinx) <git@amd.com>
> > Subject: Re: [PATCH] usb: dwc3: core: enable CCI support
> > 
> > On Fri, Oct 13, 2023, Piyush Mehta wrote:
> > > The GSBUSCFG0 register bits [31:16] are used to configure the cache
> > > type settings of the descriptor and data write/read transfers
> > > (Cacheable, Bufferable/ Posted). When CCI is enabled in the design,
> > > DWC3 core GSBUSCFG0 cache bits must be updated to support CCI enabled
> > transfers in USB.
> > >
> > > Signed-off-by: Piyush Mehta <piyush.mehta@amd.com>
> > > ---
> > > DWC3 Register Map Link:
> > > https://urldefense.com/v3/__https://docs.xilinx.com/r/en-US/ug1087-zynq-
> > ultrascale-registers/GSBUSCFG0-USB3_XHCI-
> > Register__;!!A4F2R9G_pg!cbLbYLk9xu54DZMkiTQzMhdCaPA4gmIVInes4ZeNb28
> > AI2pgesEvHNYtjoZfWvE_t7wlUdZvYn-Pio8WjA55ekal$
> > > Register Name	GSBUSCFG0
> > > Description	Global SoC Bus Configuration Register 0
> > >
> > > GSBUSCFG0 (USB3_XHCI) Register Bit-Field:
> > > DATRDREQINFO	31:28
> > > DESRDREQINFO	27:24
> > > DATWRREQINFO	23:20
> > > DESWRREQINFO	19:16
> > > ---
> > >  drivers/usb/dwc3/core.c | 17 +++++++++++++++++
> > > drivers/usb/dwc3/core.h |  5 +++++
> > >  2 files changed, 22 insertions(+)
> > >
> > > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c index
> > > 9c6bf054f15d..fc6892c63abf 100644
> > > --- a/drivers/usb/dwc3/core.c
> > > +++ b/drivers/usb/dwc3/core.c
> > > @@ -23,6 +23,7 @@
> > >  #include <linux/delay.h>
> > >  #include <linux/dma-mapping.h>
> > >  #include <linux/of.h>
> > > +#include <linux/of_address.h>
> > >  #include <linux/of_graph.h>
> > >  #include <linux/acpi.h>
> > >  #include <linux/pinctrl/consumer.h>
> > > @@ -559,6 +560,20 @@ static void dwc3_cache_hwparams(struct dwc3
> > *dwc)
> > >  		parms->hwparams9 = dwc3_readl(dwc->regs,
> > DWC3_GHWPARAMS9);  }
> > >
> > > +static void dwc3_config_soc_bus(struct dwc3 *dwc) {
> > > +	if (of_dma_is_coherent(dwc->dev->of_node)) {
> > > +		u32 reg;
> > > +
> > > +		reg = dwc3_readl(dwc->regs, DWC3_GSBUSCFG0);
> > > +		reg |= DWC3_GSBUSCFG0_DATRDREQINFO_MASK |
> > > +			DWC3_GSBUSCFG0_DESRDREQINFO_MASK |
> > > +			DWC3_GSBUSCFG0_DATWRREQINFO_MASK |
> > > +			DWC3_GSBUSCFG0_DESWRREQINFO_MASK;
> > > +		dwc3_writel(dwc->regs, DWC3_GSBUSCFG0, reg);
> > > +	}
> > > +}
> > > +
> > 
> > You're overwriting default values for all platforms. Don't do that. Not every
> > platform supports this setting. Only apply these specific settings to your
> > platform.
> 
> This DWC3_GSBUSCFG0 register is part of the DWC3/Core system. In glue/vendor drivers, I couldn't find a way to access
> the DWC3/Core access register.  Could you please provide a suggestion for the Xilinx glue driver (dwc3/dwc3-xilinx.c) to
> access dwc3 registers?

We may need to pass the hardware configuration from the dt binding.

Thanks,
Thinh