From:   Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To:     linux-wireless@vger.kernel.org
Cc:     Yan-Hsuan Chuang <tony0620emma@gmail.com>,
        Kalle Valo <kvalo@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        linux-mmc@vger.kernel.org, Chris Morgan <macroalpha82@gmail.com>,
        Nitin Gupta <nitin.gupta981@gmail.com>,
        Neo Jou <neojou@gmail.com>, Pkshih <pkshih@realtek.com>,
        Jernej Skrabec <jernej.skrabec@gmail.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Subject: [PATCH v2 RFC 5/9] wifi: rtw88: main: Reserve 8 bytes of extra TX headroom for SDIO cards
Date:   Fri, 10 Mar 2023 21:29:18 +0100
Message-Id: <20230310202922.2459680-6-martin.blumenstingl@googlemail.com>
In-Reply-To: <20230310202922.2459680-1-martin.blumenstingl@googlemail.com>
References: <20230310202922.2459680-1-martin.blumenstingl@googlemail.com>
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For SDIO host controllers with DMA support the TX buffer physical memory
address need to be aligned at an 8-byte boundary. Reserve 8 bytes of
extra TX headroom so we can align the data without re-allocating the
transmit buffer.

While here, also remove the TODO comment regarding extra headroom for
USB and SDIO. For SDIO the extra headroom is now handled and for USB it
was not needed so far.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
Changes since v1:
- none

 drivers/net/wireless/realtek/rtw88/main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/realtek/rtw88/main.c b/drivers/net/wireless/realtek/rtw88/main.c
index cdc4703ead5f..1cb553485cff 100644
--- a/drivers/net/wireless/realtek/rtw88/main.c
+++ b/drivers/net/wireless/realtek/rtw88/main.c
@@ -2163,9 +2163,11 @@ int rtw_register_hw(struct rtw_dev *rtwdev, struct ieee80211_hw *hw)
 	int max_tx_headroom = 0;
 	int ret;
 
-	/* TODO: USB & SDIO may need extra room? */
 	max_tx_headroom = rtwdev->chip->tx_pkt_desc_sz;
 
+	if (rtw_hci_type(rtwdev) == RTW_HCI_TYPE_SDIO)
+		max_tx_headroom += RTW_SDIO_DATA_PTR_ALIGN;
+
 	hw->extra_tx_headroom = max_tx_headroom;
 	hw->queues = IEEE80211_NUM_ACS;
 	hw->txq_data_size = sizeof(struct rtw_txq);
-- 
2.39.2