RE: [PATCH v4] PCI: endpoint: Add prefetch BAR support

[Shradha Todi]

Reviewed-by: Shradha Todi <shradha.t@xxxxxxxxxxx>

This patch looks useful. Can we revisit this and get it merged?

>Date:   Fri, 21 Jan 2022 12:12:56 +0800
>From:   Li Chen <lchen.firstlove@xxxxxxxxxxxx>
>To:     "Bjorn Helgaas" <helgaas@xxxxxxxxxx>
>Cc:     "Kishon Vijay Abraham I" <kishon@xxxxxx>,
>        "Lorenzo Pieralisi" <lorenzo.pieralisi@xxxxxxx>,
>        "Bjorn Helgaas" <bhelgaas@xxxxxxxxxx>,
>        "linux-pci" <linux-pci@xxxxxxxxxxxxxxx>,
>        "linux-kernel" <linux-kernel@xxxxxxxxxxxxxxx>
>Message-ID: <17e7ad65ff5.d9de88b4962.1109678039880040918@xxxxxxxxxxxx>
>In-Reply-To: 
>Subject: [PATCH v4] PCI: endpoint: Add prefetch BAR support
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>From: Li Chen <lchen@xxxxxxxxxxxxx>
>
>Before this commit, epf cannot set BAR to be prefetchable.
>Prefetchable BAR can also help epf device to use bridge's
>prefetch memory window.
>
>Signed-off-by: Li Chen <lchen@xxxxxxxxxxxxx>
>---
>Changes in v2:
>Remove Gerrit Change-id
>Changes in v3:
>capitalize "BAR" in the subject and commit log as suggested by Bjorn.
>Changes in v4:
>This patch context doesn't change but resend with my Zoho mail account in that previous
>company mail will contain un-removeable proprietary messages. 
>Add "From:" to the first line of the message body.
>
> drivers/pci/endpoint/functions/pci-epf-test.c | 4 ++++
> include/linux/pci-epc.h                       | 2 ++
> 2 files changed, 6 insertions(+)
>
>diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
>index 90d84d3bc868..96489cfdf58d 100644
>--- a/drivers/pci/endpoint/functions/pci-epf-test.c
>+++ b/drivers/pci/endpoint/functions/pci-epf-test.c
>@@ -817,15 +817,19 @@ static void pci_epf_configure_bar(struct pci_epf *epf,
> {
> 	struct pci_epf_bar *epf_bar;
> 	bool bar_fixed_64bit;
>+	bool bar_prefetch;
> 	int i;
> 
> 	for (i = 0; i < PCI_STD_NUM_BARS; i++) {
> 		epf_bar = &epf->bar[i];
> 		bar_fixed_64bit = !!(epc_features->bar_fixed_64bit & (1 << i));
>+		bar_prefetch = !!(epc_features->bar_prefetch & (1 << i));
> 		if (bar_fixed_64bit)
> 			epf_bar->flags |= PCI_BASE_ADDRESS_MEM_TYPE_64;
> 		if (epc_features->bar_fixed_size[i])
> 			bar_size[i] = epc_features->bar_fixed_size[i];
>+		if (bar_prefetch)
>+			epf_bar->flags |= PCI_BASE_ADDRESS_MEM_PREFETCH;
> 	}
> }
> 
>diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
>index a48778e1a4ee..825632d581d0 100644
>--- a/include/linux/pci-epc.h
>+++ b/include/linux/pci-epc.h
>@@ -161,6 +161,7 @@ struct pci_epc {
>  * @msix_capable: indicate if the endpoint function has MSI-X capability
>  * @reserved_bar: bitmap to indicate reserved BAR unavailable to function driver
>  * @bar_fixed_64bit: bitmap to indicate fixed 64bit BARs
>+ * @bar_prefetch: bitmap to indicate prefetchable BARs
>  * @bar_fixed_size: Array specifying the size supported by each BAR
>  * @align: alignment size required for BAR buffer allocation
>  */
>@@ -171,6 +172,7 @@ struct pci_epc_features {
> 	unsigned int	msix_capable : 1;
> 	u8	reserved_bar;
> 	u8	bar_fixed_64bit;
>+	u8	bar_prefetch;
> 	u64	bar_fixed_size[PCI_STD_NUM_BARS];
> 	size_t	align;
> };
>-- 
>2.34.1
>
>
>