brcmfmac: add comment block in brcmf_sdio_buscore_read()

In brcmf_sdio_buscore_read() there is some special handling upon
register access to chipid register of the chipcommon core. Add
comment explaining why it is done here.

Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
index 81eb776..0868614 100644 (file)
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
@@ -3772,6 +3772,13 @@ static u32 brcmf_sdio_buscore_read32(void *ctx, u32 addr)
 
        val = brcmf_sdiod_readl(sdiodev, addr, NULL);
 
+       /*
+        * this is a bit of special handling if reading the chipcommon chipid
+        * register. The 4339 is a next-gen of the 4335. It uses the same
+        * SDIO device id as 4335 and the chipid register returns 4335 as well.
+        * It can be identified as 4339 by looking at the chip revision. It
+        * is corrected here so the chip.c module has the right info.
+        */
        if (addr == CORE_CC_REG(SI_ENUM_BASE, chipid) &&
            (sdiodev->func1->device == SDIO_DEVICE_ID_BROADCOM_4339 ||
             sdiodev->func1->device == SDIO_DEVICE_ID_BROADCOM_4335_4339)) {