RE: [PATCH v11 1/6] PCI: designware: move calculation of bus addresses to DRA7xx

-----Original Message-----
From: Bjorn Helgaas [mailto:helgaas@kernel.org]
Sent: 21 October 2015 23:15
To: Wangzhou (B)
Cc: Bjorn Helgaas; jingoohan1@gmail.com; pratyush.anand@gmail.com; Arnd
Bergmann; linux@arm.linux.org.uk; thomas.petazzoni@free-electrons.com;
Gabriele Paoloni; lorenzo.pieralisi@arm.com; james.morse@arm.com;
Liviu.Dudau@arm.com; jason@lakedaemon.net; robh@kernel.org;
gabriel.fernandez@linaro.org; Minghuan.Lian@freescale.com; linux-
pci@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
devicetree@vger.kernel.org; linux-kernel@vger.kernel.org; zhangjukuo;
qiuzhenfa; liudongdong (C); qiujiang; xuwei (O); Liguozhu (Kenneth)
Subject: Re: [PATCH v11 1/6] PCI: designware: move calculation of bus
addresses to DRA7xx

Hi Zhou & Gabriele,

Hi Bjorn, thanks for reviewing

On Fri, Oct 16, 2015 at 06:23:36PM +0800, Zhou Wang wrote:

quoted

From: gabriele paoloni <redacted>

Commit f4c55c5a3f7f ("PCI: designware: Program ATU with untranslated
address") added the calculation of PCI BUS addresses in designware,
storing them in new fields added in "struct pcie_port". This
calculation is done for every designware user even if is only
applicable to DRA7xx.
This patch moves the calculation of the bus addresses to the DRA7xx
driver and is needed to allow the rework of designware to use
the new DT parsing API.

Signed-off-by: Gabriele Paoloni <redacted>
Signed-off-by: Zhou Wang <wangzhou1@hisilicon.com>
Acked-by: Pratyush Anand <pratyush.anand@gmail.com>
---
 drivers/pci/host/pci-dra7xx.c      | 13 +++++++++++++
 drivers/pci/host/pcie-designware.c | 15 ++++-----------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
index 199e29a..ebdffa0 100644
--- a/drivers/pci/host/pci-dra7xx.c
+++ b/drivers/pci/host/pci-dra7xx.c

@@ -62,6 +62,7 @@

 #define	PCIECTRL_DRA7XX_CONF_PHY_CS			0x010C
 #define	LINK_UP						BIT(16)
+#define	CPU_TO_BUS_ADDR					0x0FFFFFFF

"CPU_TO_BUS_ADDR" is a very generic name.  Since you do have DRA7XX in
other #defines and static symbols in this file, maybe it could be DRA7XX to
make it obvious that it only applies here?

Ok will change to DRA7XX_CPU_TO_BUS_ADRR in v12

quoted

 struct dra7xx_pcie {
 	void __iomem		*base;

@@ -151,6 +152,18 @@ static void dra7xx_pcie_enable_interrupts(struct

pcie_port *pp)

quoted

 static void dra7xx_pcie_host_init(struct pcie_port *pp)
 {
 	dw_pcie_setup_rc(pp);
+
+	if (pp->io_mod_base)
+		pp->io_mod_base &= CPU_TO_BUS_ADDR;

These are equivalent to

  pp->io_mod_base &= CPU_TO_BUS_ADDR;

(You don't need to test whether they're zero first.)

Yes agreed, will change in v12

quoted

+
+	if (pp->mem_mod_base)
+		pp->mem_mod_base &= CPU_TO_BUS_ADDR;
+
+	if (pp->cfg0_mod_base) {
+		pp->cfg0_mod_base &= CPU_TO_BUS_ADDR;
+		pp->cfg1_mod_base &= CPU_TO_BUS_ADDR;
+	}
+
 	dra7xx_pcie_establish_link(pp);
 	if (IS_ENABLED(CONFIG_PCI_MSI))
 		dw_pcie_msi_init(pp);

diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-

designware.c

quoted

index 52aa6e3..75338a6 100644

--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c

@@ -365,14 +365,10 @@ int dw_pcie_host_init(struct pcie_port *pp)
 	struct of_pci_range range;
 	struct of_pci_range_parser parser;
 	struct resource *cfg_res;
-	u32 val, na, ns;
+	u32 val, ns;
 	const __be32 *addrp;
 	int i, index, ret;

-	/* Find the address cell size and the number of cells in order to get
-	 * the untranslated address.
-	 */
-	of_property_read_u32(np, "#address-cells", &na);
 	ns = of_n_size_cells(np);

 	cfg_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config");

@@ -415,8 +411,7 @@ int dw_pcie_host_init(struct pcie_port *pp)
 			pp->io_base = range.cpu_addr;

 			/* Find the untranslated IO space address */
-			pp->io_mod_base = of_read_number(parser.range -
-							 parser.np + na, ns);
+			pp->io_mod_base = range.cpu_addr;

So apparently

  "of_read_number() == range.cpu_addr & CPU_TO_BUS_ADDR" on DRA7xx
  "of_read_number() == range.cpu_addr" everywhere else?

Yes correct

Is that right?  Is that a valid assumption, i.e., are we assuming
anything about DTs in the field that we shouldn't?

Before I wrote a patch that was generic to accommodate intermediate level
of translation between PCI_addr -> BUS_addr -> CPU_addr

http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/360922.html

After discussion we agreed to solve it with a bitmask rather than adding
a field to of_pci_range to make it generic.
The bitmask only applies to DRA7xx

quoted

 		}
 		if (restype == IORESOURCE_MEM) {
 			of_pci_range_to_resource(&range, np, &pp->mem);

@@ -425,8 +420,7 @@ int dw_pcie_host_init(struct pcie_port *pp)
 			pp->mem_bus_addr = range.pci_addr;

 			/* Find the untranslated MEM space address */
-			pp->mem_mod_base = of_read_number(parser.range -
-							  parser.np + na, ns);
+			pp->mem_mod_base = range.cpu_addr;
 		}
 		if (restype == 0) {
 			of_pci_range_to_resource(&range, np, &pp->cfg);

@@ -436,8 +430,7 @@ int dw_pcie_host_init(struct pcie_port *pp)
 			pp->cfg1_base = pp->cfg.start + pp->cfg0_size;

 			/* Find the untranslated configuration space address */
-			pp->cfg0_mod_base = of_read_number(parser.range -
-							   parser.np + na, ns);
+			pp->cfg0_mod_base = range.cpu_addr;
 			pp->cfg1_mod_base = pp->cfg0_mod_base +
 					    pp->cfg0_size;
 		}
--

1.9.1

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