Hi Suman,

On Wednesday 13 January 2016 11:21 PM, Suman Anna wrote:

On 01/13/2016 12:47 AM, Kishon Vijay Abraham I wrote:

quoted

Use platform populated reset assert and deassert
callbacks to perform reset of PCIe.

Use these callbacks until a reset interface using drivers/reset
is available for the purpose.

Signed-off-by: Kishon Vijay Abraham I <redacted>
Signed-off-by: Sekhar Nori <redacted>
---
 drivers/pci/host/pci-dra7xx.c |   32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
index 8c36880..049083d 100644
--- a/drivers/pci/host/pci-dra7xx.c
+++ b/drivers/pci/host/pci-dra7xx.c

@@ -25,6 +25,8 @@
 #include <linux/resource.h>
 #include <linux/types.h>
 
+#include <linux/platform_data/pci-dra7xx.h>
+
 #include "pcie-designware.h"
 
 /* PCIe controller wrapper DRA7XX configuration registers */

@@ -329,6 +331,32 @@ static int __init dra7xx_add_pcie_port(struct dra7xx_pcie *dra7xx,
 	return 0;
 }
 
+static int dra7xx_pcie_reset(struct platform_device *pdev)
+{
+	int ret;
+	struct device *dev = &pdev->dev;
+	struct pci_dra7xx_platform_data *pdata = pdev->dev.platform_data;
+
+	if (!(pdata && pdata->deassert_reset && pdata->assert_reset)) {
+		dev_err(dev, "platform data for reset not found!\n");
+		return -EINVAL;
+	}
+
+	ret = pdata->assert_reset(pdev, pdata->reset_name);
+	if (ret) {
+		dev_err(dev, "assert_reset failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = pdata->deassert_reset(pdev, pdata->reset_name);
+	if (ret) {
+		dev_err(dev, "deassert_reset failed: %d\n", ret);
+		return ret;
+	}

The only comment I have on this is the symmetry (assert_reset invocation
in driver remove). If you install and remove the module once, then the
reset stays deasserted. On Power-On-Reset, the resets by default will be
in asserted state.

hmm.. not sure of the benefits of leaving the reset lines de-asserted during
remove. The idea is irrespective of the initial sate or power-on state, during
probe the driver should assert and de-assert the reset lines.

Thanks
Kishon