Hi Loic,
On 11/13/20 6:59 AM, Loic Poulain wrote:
Ensure that the device is hard-reset on remove to restore its initial
state and avoid further issues on subsequent probe.
This has been tested with Telit FN980m module.
Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
---
drivers/bus/mhi/pci_generic.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/bus/mhi/pci_generic.c b/drivers/bus/mhi/pci_generic.c
index 13a7e4f..09c6b26 100644
--- a/drivers/bus/mhi/pci_generic.c
+++ b/drivers/bus/mhi/pci_generic.c
@@ -15,6 +15,8 @@
#define MHI_PCI_DEFAULT_BAR_NUM 0
+#define DEV_RESET_REG (0xB0)
+
/**
* struct mhi_pci_dev_info - MHI PCI device specific information
* @config: MHI controller configuration
@@ -166,6 +168,11 @@ static void mhi_pci_status_cb(struct mhi_controller *mhi_cntrl,
/* Nothing to do for now */
}
+static inline void mhi_pci_reset(struct mhi_controller *mhi_cntrl)
+{
+ writel(1, mhi_cntrl->regs + DEV_RESET_REG);
+}
+
static int mhi_pci_claim(struct mhi_controller *mhi_cntrl,
unsigned int bar_num, u64 dma_mask)
{
@@ -329,6 +336,10 @@ static void mhi_pci_remove(struct pci_dev *pdev)
mhi_power_down(mhi_cntrl, true);
mhi_unprepare_after_power_down(mhi_cntrl);
mhi_unregister_controller(mhi_cntrl);
+
+ /* MHI-layer reset could not be enough, always hard-reset the device */
+ mhi_pci_reset(mhi_cntrl);
Referring to MHI spec:
Hosts writes this register to trigger a reset. This can be used when the
host detects a timeout in the MHI protocol and can use the reset as a
last resort to recover the device. Host should first attempt an MHI
Reset procedure before resetting the entire device.
What issue are you facing which requires you to do full device reset ?
Based on the spec recommendation, looks like this should be a last resort.
Thanks,
Hemant
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