* [PATCH v2] i2c: tegra: Maintain CPU endianness
@ 2015-01-22 18:12 Dmitry Osipenko
[not found] ` <1421950352-26515-1-git-send-email-digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
0 siblings, 1 reply; 2+ messages in thread
From: Dmitry Osipenko @ 2015-01-22 18:12 UTC (permalink / raw)
To: digetx-Re5JQEeQqe8AvxtiuMwx3w, Wolfram Sang, Stephen Warren,
Thierry Reding, Alexandre Courbot, Laxman Dewangan
Cc: Ben Dooks, Bob Mottram, linux-tegra-u79uwXL29TY76Z2rM5mHXA,
linux-i2c-u79uwXL29TY76Z2rM5mHXA,
linux-kernel-u79uwXL29TY76Z2rM5mHXA
Support CPU BE mode by adding endianness conversion for memcpy interactions.
Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
Changelog:
v2: For consistency cpu_to_le32() changed to le32_to_cpu() because
i2c_writel() takes BE value in BE CPU mode and value is in LE format.
drivers/i2c/busses/i2c-tegra.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 28b87e6..b5afb9f 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -286,6 +286,7 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
if (rx_fifo_avail > 0 && buf_remaining > 0) {
BUG_ON(buf_remaining > 3);
val = i2c_readl(i2c_dev, I2C_RX_FIFO);
+ val = cpu_to_le32(val);
memcpy(buf, &val, buf_remaining);
buf_remaining = 0;
rx_fifo_avail--;
@@ -343,7 +344,9 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
*/
if (tx_fifo_avail > 0 && buf_remaining > 0) {
BUG_ON(buf_remaining > 3);
+ val = 0;
memcpy(&val, buf, buf_remaining);
+ val = le32_to_cpu(val);
/* Again update before writing to FIFO to make sure isr sees. */
i2c_dev->msg_buf_remaining = 0;
--
2.2.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] i2c: tegra: Maintain CPU endianness
[not found] ` <1421950352-26515-1-git-send-email-digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
@ 2015-01-23 9:10 ` Alexandre Courbot
0 siblings, 0 replies; 2+ messages in thread
From: Alexandre Courbot @ 2015-01-23 9:10 UTC (permalink / raw)
To: Dmitry Osipenko
Cc: Wolfram Sang, Stephen Warren, Thierry Reding, Laxman Dewangan,
Ben Dooks, Bob Mottram,
linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
Linux Kernel Mailing List
On Fri, Jan 23, 2015 at 3:12 AM, Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Support CPU BE mode by adding endianness conversion for memcpy interactions.
>
> Signed-off-by: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
> Changelog:
> v2: For consistency cpu_to_le32() changed to le32_to_cpu() because
> i2c_writel() takes BE value in BE CPU mode and value is in LE format.
>
> drivers/i2c/busses/i2c-tegra.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 28b87e6..b5afb9f 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -286,6 +286,7 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
> if (rx_fifo_avail > 0 && buf_remaining > 0) {
> BUG_ON(buf_remaining > 3);
> val = i2c_readl(i2c_dev, I2C_RX_FIFO);
> + val = cpu_to_le32(val);
> memcpy(buf, &val, buf_remaining);
> buf_remaining = 0;
> rx_fifo_avail--;
> @@ -343,7 +344,9 @@ static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
> */
> if (tx_fifo_avail > 0 && buf_remaining > 0) {
> BUG_ON(buf_remaining > 3);
> + val = 0;
> memcpy(&val, buf, buf_remaining);
> + val = le32_to_cpu(val);
Ok, with le32_to_cpu() this makes sense now. memcpying part of an int
will keep the lowest byte at the lowest address, so this should work
for little-endian.
Acked-by: Alexandre Courbot <acourbot-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
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2015-01-22 18:12 [PATCH v2] i2c: tegra: Maintain CPU endianness Dmitry Osipenko
[not found] ` <1421950352-26515-1-git-send-email-digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2015-01-23 9:10 ` Alexandre Courbot
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