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Message-ID: <Zh/ezLdct9sisvhc@lizhi-Precision-Tower-5810>
Date: Wed, 17 Apr 2024 10:38:04 -0400
From: Frank Li <Frank.li@....com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Jingoo Han <jingoohan1@...il.com>,
Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
Lorenzo Pieralisi <lpieralisi@...nel.org>,
Krzysztof Wilczyński <kw@...ux.com>,
Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>, imx@...ts.linux.dev,
linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org
Subject: Re: [PATCH v6 5/5] PCI: dwc: Add generic MSG TLP support for sending
PME_Turn_Off when system suspend
On Wed, Apr 17, 2024 at 03:49:44PM +0530, Manivannan Sadhasivam wrote:
> On Mon, Apr 15, 2024 at 03:33:29PM -0400, Frank Li wrote:
> > Instead of relying on the vendor specific implementations to send the
> > PME_Turn_Off message, let's introduce a generic way of sending the message
> > using the MSG TLP.
> >
> > This is achieved by reserving a region for MSG TLP of size
> > 'pci->region_align', at the end of the first IORESOURCE_MEM window of the
> > host bridge. And then sending the PME_Turn_Off message during system
> > suspend with the help of iATU.
> >
> > The reserve space at end is a little bit better than alloc_resource()
> > because the below reasons.
> > - alloc_resource() will allocate space at begin of IORESOURCE_MEM window.
> > There will be a hole when first Endpoint Device (EP) try to alloc a bigger
> > space then 'region_align' size.
> > - Keep EP device's IORESOURCE_MEM space unchange with/without this patch.
> >
>
> I'd rewrite the above sentence as:
>
> 'The reason for reserving the MSG TLP region at the end of the
> IORESOURCE_MEM is to avoid generating holes in between. Because, when the region
> is allocated using allocate_resource(), memory will be allocated from the start
> of the window. Later, if memory gets allocated for an endpoint of size bigger
> than 'region_align', there will be a hole between MSG TLP region and endpoint
> memory.'
>
> > It should be noted that this generic implementation is optional for the
> > glue drivers and can be overridden by a custom 'pme_turn_off' callback.
> >
> > Signed-off-by: Frank Li <Frank.Li@....com>
> > ---
> > drivers/pci/controller/dwc/pcie-designware-host.c | 94 ++++++++++++++++++++++-
> > drivers/pci/controller/dwc/pcie-designware.h | 3 +
> > 2 files changed, 93 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 3a9cb4be22ab2..5001cdf220123 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -398,6 +398,31 @@ static int dw_pcie_msi_host_init(struct dw_pcie_rp *pp)
> > return 0;
> > }
> >
> > +static void dw_pcie_host_request_msg_tlp_res(struct dw_pcie_rp *pp)
> > +{
> > + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > + struct resource_entry *win;
> > + struct resource *res;
> > +
> > + win = resource_list_first_type(&pp->bridge->windows, IORESOURCE_MEM);
> > + if (win) {
> > + res = devm_kzalloc(pci->dev, sizeof(*res), GFP_KERNEL);
> > + if (!res)
> > + return;
> > +
> > + /* Reserve last region_align block as message TLP space */
>
> /*
> * Allocate MSG TLP region of size 'region_align' at the end of
> * the host bridge window.
> */
>
> > + res->start = win->res->end - pci->region_align + 1;
> > + res->end = win->res->end;
> > + res->name = "msg";
> > + res->flags = win->res->flags | IORESOURCE_BUSY;
> > +
> > + if (!devm_request_resource(pci->dev, win->res, res))
> > + pp->msg_res = res;
> > + else
> > + devm_kfree(pci->dev, res);
>
> You are explicitly freeing 'msg_res' everywhere. So either drop devm_ or rely
> on devm to free the memory.
>
> > + }
> > +}
> > +
> > int dw_pcie_host_init(struct dw_pcie_rp *pp)
> > {
> > struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> > @@ -484,6 +509,16 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> >
> > dw_pcie_iatu_detect(pci);
> >
> > + /*
> > + * Allocate the resource for MSG TLP before programming the iATU outbound window in
> > + * dw_pcie_setup_rc(). Since the allocation depends on the value of 'region_align', this has
> > + * to be done after dw_pcie_iatu_detect().
>
> Please wrap the comments to 80 columns.
New code style is 100 columns. does comments still stick to 80 columns?
>
> > + *
> > + * Glue driver need set use_atu_msg before dw_pcie_host_init() if want MSG TLP feature.
>
> How about,
>
> * Glue drivers need to set 'use_atu_msg' before dw_pcie_host_init() to
> * make use of the generic MSG TLP implementation.
>
> > + */
> > + if (pp->use_atu_msg)
> > + dw_pcie_host_request_msg_tlp_res(pp);
> > +
> > ret = dw_pcie_edma_detect(pci);
> > if (ret)
> > goto err_free_msi;
> > @@ -541,6 +576,11 @@ void dw_pcie_host_deinit(struct dw_pcie_rp *pp)
> >
> > dw_pcie_edma_remove(pci);
> >
> > + if (pp->msg_res) {
> > + release_resource(pp->msg_res);
> > + devm_kfree(pci->dev, pp->msg_res);
> > + }
> > +
> > if (pp->has_msi_ctrl)
> > dw_pcie_free_msi(pp);
> >
> > @@ -702,6 +742,10 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> > atu.pci_addr = entry->res->start - entry->offset;
> > atu.size = resource_size(entry->res);
> >
> > + /* MSG TLB window resource reserve at one of end of IORESOURCE_MEM resource */
>
> How about,
>
> /* Adjust iATU size if MSG TLP region was allocated before */
> if (pp->msg_res && pp->msg_res->parent == entry->res)
> atu.size = resource_size(entry->res) -
> resource_size(pp->msg_res);
> else
> atu.size = resource_size(entry->res);
>
> > + if (pp->msg_res && pp->msg_res->parent == entry->res)
> > + atu.size -= resource_size(pp->msg_res);
> > +
> > ret = dw_pcie_prog_outbound_atu(pci, &atu);
> > if (ret) {
> > dev_err(pci->dev, "Failed to set MEM range %pr\n",
> > @@ -733,6 +777,8 @@ static int dw_pcie_iatu_setup(struct dw_pcie_rp *pp)
> > dev_warn(pci->dev, "Ranges exceed outbound iATU size (%d)\n",
> > pci->num_ob_windows);
> >
> > + pp->msg_atu_index = i;
> > +
> > i = 0;
> > resource_list_for_each_entry(entry, &pp->bridge->dma_ranges) {
> > if (resource_type(entry->res) != IORESOURCE_MEM)
> > @@ -838,11 +884,48 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> > }
> > EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
> >
> > +/* Using message outbound ATU to send out PME_Turn_Off message for dwc PCIe controller */
>
> No need of this comment.
>
> > +static int dw_pcie_pme_turn_off(struct dw_pcie *pci)
> > +{
> > + struct dw_pcie_ob_atu_cfg atu = { 0 };
> > + void __iomem *mem;
> > + int ret;
> > +
> > + if (pci->num_ob_windows <= pci->pp.msg_atu_index)
> > + return -EINVAL;
>
> return -ENOSPC;
>
> > +
> > + if (!pci->pp.msg_res)
> > + return -EINVAL;
>
> return -ENOSPC;
> - Mani
>
> --
> மணிவண்ணன் சதாசிவம்
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