On 6/27/2019 9:20 PM, Lorenzo Pieralisi wrote:

On Thu, Jun 27, 2019 at 09:03:08PM +0530, Vidya Sagar wrote:

quoted

On 6/27/2019 8:28 PM, Lorenzo Pieralisi wrote:

quoted

On Mon, Jun 24, 2019 at 02:44:56PM +0530, Vidya Sagar wrote:

quoted

Remove multiple write enable and disable sequences of dbi registers as
Tegra194 implements writes to BAR-0 register (offset: 0x10) controlled by
DBI write-lock enable bit thereby not allowing any further writes to BAR-0
register in config space to take place. Hence enabling write permission at
the start of function and disabling the same only towards the end.

I do not understand what this patch does, I would like to rephrase
the commit log in a way that is easier to parse.

In particular I do not get what you mean in relation to BAR-0, I am
confused, please clarify.

Lorenzo

Well, some of the Synopsys DesignWare core's DBI registers are
protected with a lock without which, they are read-only by default.
Existing code in dw_pcie_setup_rc() API tries to unlock and lock
multiple times whenever it wants to update those write-protected
registers. This patch attempts to unlock all such write-protected
registers for writing once in the beginning of the function and lock
them back towards the end.  As far as BAR-0 register (which is at
offset 0x10 in DBI space... nothing but the config space) in Tegra194
is concerned, it is one of those registers to which writes are
protected. I could have added unlock/lock pair around accessing this
register, but that would bloat this API with one more pair of
unlock/lock, instead I chose to remove unlock/lock pairs for all
protected registers and have unlock in the beginning and lock towards
the end.

Ok, so DBI space registers that require write permissions are per-IP.
This is clearer so the commit log must be rewritten, it is not clear at
all in this respect at least not as-is, if you read it you will
notice ;-)

Ok. I'll update commit message in next patch series.

-Vidya Sagar

Lorenzo

quoted

-Vidya Sagar

quoted

quoted

Signed-off-by: Vidya Sagar <redacted>
Reviewed-by: Thierry Reding <redacted>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
---
Changes since [v10]:
* None

Changes since [v9]:
* None

Changes since [v8]:
* None

Changes since [v7]:
* None

Changes since [v6]:
* None

Changes since [v5]:
* Moved write enable to the beginning of the API and write disable to the end

Changes since [v4]:
* None

Changes since [v3]:
* None

Changes since [v2]:
* None

Changes since [v1]:
* None

   drivers/pci/controller/dwc/pcie-designware-host.c | 14 ++++++++------
   1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index f93252d0da5b..d3156446ff27 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c

@@ -628,6 +628,12 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
   	u32 val, ctrl, num_ctrls;
   	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	/*
+	 * Enable DBI read-only registers for writing/updating configuration.
+	 * Write permission gets disabled towards the end of this function.
+	 */
+	dw_pcie_dbi_ro_wr_en(pci);
+
   	dw_pcie_setup(pci);
   	if (!pp->ops->msi_host_init) {

@@ -650,12 +656,10 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
   	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_1, 0x00000000);
   	/* Setup interrupt pins */
-	dw_pcie_dbi_ro_wr_en(pci);
   	val = dw_pcie_readl_dbi(pci, PCI_INTERRUPT_LINE);
   	val &= 0xffff00ff;
   	val |= 0x00000100;
   	dw_pcie_writel_dbi(pci, PCI_INTERRUPT_LINE, val);
-	dw_pcie_dbi_ro_wr_dis(pci);
   	/* Setup bus numbers */
   	val = dw_pcie_readl_dbi(pci, PCI_PRIMARY_BUS);

@@ -687,15 +691,13 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
   	dw_pcie_wr_own_conf(pp, PCI_BASE_ADDRESS_0, 4, 0);
-	/* Enable write permission for the DBI read-only register */
-	dw_pcie_dbi_ro_wr_en(pci);
   	/* Program correct class for RC */
   	dw_pcie_wr_own_conf(pp, PCI_CLASS_DEVICE, 2, PCI_CLASS_BRIDGE_PCI);
-	/* Better disable write permission right after the update */
-	dw_pcie_dbi_ro_wr_dis(pci);
   	dw_pcie_rd_own_conf(pp, PCIE_LINK_WIDTH_SPEED_CONTROL, 4, &val);
   	val |= PORT_LOGIC_SPEED_CHANGE;
   	dw_pcie_wr_own_conf(pp, PCIE_LINK_WIDTH_SPEED_CONTROL, 4, val);
+
+	dw_pcie_dbi_ro_wr_dis(pci);
   }
   EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);

-- 
2.17.1

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