[PATCH for-4.4-stable] ath10k: restore QCA9880-AR1A (v1) detection

[Christian Lamparter <chunkeey@gmail.com>]

commit f8914a14623a79b73f72b2b1ee4cd9b2cb91b735 upstream
---
From f8914a14623a79b73f72b2b1ee4cd9b2cb91b735 Mon Sep 17 00:00:00 2001
From: Christian Lamparter <chunkeey@gmail.com>
Date: Mon, 25 Mar 2019 13:50:19 +0100
Subject: [PATCH 4.4] ath10k: restore QCA9880-AR1A (v1) detection
To: linux-wireless@vger.kernel.org,
    ath10k@lists.infradead.org
Cc: Kalle Valo <kvalo@codeaurora.org>

This patch restores the old behavior that read
the chip_id on the QCA988x before resetting the
chip. This needs to be done in this order since
the unsupported QCA988x AR1A chips fall off the
bus when resetted. Otherwise the next MMIO Op
after the reset causes a BUS ERROR and panic.

Cc: stable@vger.kernel.org # 4.4
Fixes: 1a7fecb766c8 ("ath10k: reset chip before reading chip_id in probe")
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
---
 drivers/net/wireless/ath/ath10k/pci.c | 36 +++++++++++++++++++--------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c
--- a/drivers/net/wireless/ath/ath10k/pci.c	2019-09-08 00:07:21.374565470 +0200
+++ b/drivers/net/wireless/ath/ath10k/pci.c	2019-09-08 00:17:15.365912133 +0200
@@ -2988,12 +2988,13 @@ static int ath10k_pci_probe(struct pci_d
 	struct ath10k_pci *ar_pci;
 	enum ath10k_hw_rev hw_rev;
 	u32 chip_id;
-	bool pci_ps;
+	bool pci_ps, is_qca988x = false;
 
 	switch (pci_dev->device) {
 	case QCA988X_2_0_DEVICE_ID:
 		hw_rev = ATH10K_HW_QCA988X;
 		pci_ps = false;
+		is_qca988x = true;
 		break;
 	case QCA6164_2_1_DEVICE_ID:
 	case QCA6174_2_1_DEVICE_ID:
@@ -3087,6 +3088,19 @@ static int ath10k_pci_probe(struct pci_d
 		goto err_deinit_irq;
 	}
 
+	/* Read CHIP_ID before reset to catch QCA9880-AR1A v1 devices that
+	 * fall off the bus during chip_reset. These chips have the same pci
+	 * device id as the QCA9880 BR4A or 2R4E. So that's why the check.
+	 */
+	if (is_qca988x) {
+		chip_id = ath10k_pci_soc_read32(ar, SOC_CHIP_ID_ADDRESS);
+		if (chip_id != 0xffffffff) {
+			if (!ath10k_pci_chip_is_supported(pdev->device,
+							  chip_id))
+				goto err_unsupported;
+		}
+	}
+
 	ret = ath10k_pci_chip_reset(ar);
 	if (ret) {
 		ath10k_err(ar, "failed to reset chip: %d\n", ret);
@@ -3099,11 +3113,8 @@ static int ath10k_pci_probe(struct pci_d
 		goto err_free_irq;
 	}
 
-	if (!ath10k_pci_chip_is_supported(pdev->device, chip_id)) {
-		ath10k_err(ar, "device %04x with chip_id %08x isn't supported\n",
-			   pdev->device, chip_id);
-		goto err_free_irq;
-	}
+	if (!ath10k_pci_chip_is_supported(pdev->device, chip_id))
+		goto err_unsupported;
 
 	ret = ath10k_core_register(ar, chip_id);
 	if (ret) {
@@ -3113,6 +3124,10 @@ static int ath10k_pci_probe(struct pci_d
 
 	return 0;
 
+err_unsupported:
+	ath10k_err(ar, "device %04x with chip_id %08x isn't supported\n",
+		   pdev->device, bus_params.chip_id);
+
 err_free_irq:
 	ath10k_pci_free_irq(ar);
 	ath10k_pci_kill_tasklet(ar);