LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Guenter Roeck <linux@roeck-us.net>
To: Mark Brown <broonie@kernel.org>
Cc: Matthias Brugger <matthias.bgg@gmail.com>,
	linux-spi@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
	Guenter Roeck <linux@roeck-us.net>,
	Peter Hess <peter.hess@ph-home.de>,
	Frank Wunderlich <frank-w@public-files.de>,
	Tzung-Bi Shih <tzungbi@google.com>,
	Hsin-Yi Wang <hsinyi@google.com>
Subject: [PATCH] spi: mediatek: Fix fifo transfer
Date: Sun,  1 Aug 2021 20:00:23 -0700	[thread overview]
Message-ID: <20210802030023.1748777-1-linux@roeck-us.net> (raw)

Commit 3a70dd2d0503 ("spi: mediatek: fix fifo rx mode") claims that
fifo RX mode was never handled, and adds the presumably missing code
to the FIFO transfer function. However, the claim that receive data
was not handled is incorrect. It was handled as part of interrupt
handling after the transfer was complete. The code added with the above
mentioned commit reads data from the receive FIFO before the transfer
is started, which is wrong. This results in an actual transfer error
on a Hayato Chromebook.

Remove the code trying to handle receive data before the transfer is
started to fix the problem.

Fixes: 3a70dd2d0503 ("spi: mediatek: fix fifo rx mode")
Cc: Peter Hess <peter.hess@ph-home.de>
Cc: Frank Wunderlich <frank-w@public-files.de>
Cc: Tzung-Bi Shih <tzungbi@google.com>
Cc: Hsin-Yi Wang <hsinyi@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/spi/spi-mt65xx.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/spi/spi-mt65xx.c b/drivers/spi/spi-mt65xx.c
index 68dca8ceb3ad..7914255521c3 100644
--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -426,24 +426,15 @@ static int mtk_spi_fifo_transfer(struct spi_master *master,
 	mtk_spi_prepare_transfer(master, xfer);
 	mtk_spi_setup_packet(master);
 
-	cnt = xfer->len / 4;
-	if (xfer->tx_buf)
+	if (xfer->tx_buf) {
+		cnt = xfer->len / 4;
 		iowrite32_rep(mdata->base + SPI_TX_DATA_REG, xfer->tx_buf, cnt);
-
-	if (xfer->rx_buf)
-		ioread32_rep(mdata->base + SPI_RX_DATA_REG, xfer->rx_buf, cnt);
-
-	remainder = xfer->len % 4;
-	if (remainder > 0) {
-		reg_val = 0;
-		if (xfer->tx_buf) {
+		remainder = xfer->len % 4;
+		if (remainder > 0) {
+			reg_val = 0;
 			memcpy(&reg_val, xfer->tx_buf + (cnt * 4), remainder);
 			writel(reg_val, mdata->base + SPI_TX_DATA_REG);
 		}
-		if (xfer->rx_buf) {
-			reg_val = readl(mdata->base + SPI_RX_DATA_REG);
-			memcpy(xfer->rx_buf + (cnt * 4), &reg_val, remainder);
-		}
 	}
 
 	mtk_spi_enable_transfer(master);
-- 
2.25.1


             reply	other threads:[~2021-08-02  3:00 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02  3:00 Guenter Roeck [this message]
2021-08-02  3:27 ` Tzung-Bi Shih
2021-08-02  3:40   ` Hsin-Yi Wang
2021-08-02 13:57 ` Guenter Roeck
2021-08-03 22:35 ` Mark Brown

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210802030023.1748777-1-linux@roeck-us.net \
    --to=linux@roeck-us.net \
    --cc=broonie@kernel.org \
    --cc=frank-w@public-files.de \
    --cc=hsinyi@google.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mediatek@lists.infradead.org \
    --cc=linux-spi@vger.kernel.org \
    --cc=matthias.bgg@gmail.com \
    --cc=peter.hess@ph-home.de \
    --cc=tzungbi@google.com \
    --subject='Re: [PATCH] spi: mediatek: Fix fifo transfer' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).