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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: [RFC PATCH v1 15/19] rtw88: main: Reserve 8 bytes of extra TX headroom for SDIO based cards
Date:   Wed, 28 Dec 2022 00:30:16 +0100
Message-Id: <20221227233020.284266-16-martin.blumenstingl@googlemail.com>
In-Reply-To: <20221227233020.284266-1-martin.blumenstingl@googlemail.com>
References: <20221227233020.284266-1-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>
---
 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 9435cb43d1dc..bcdf1f8c8450 100644
--- a/drivers/net/wireless/realtek/rtw88/main.c
+++ b/drivers/net/wireless/realtek/rtw88/main.c
@@ -2161,9 +2161,11 @@ 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);
-- 
2.39.0