[PATCH] [SPI] SPI100k: Fix 8-bit and RX-only transfers

[PATCH] [SPI] SPI100k: Fix 8-bit and RX-only transfers

[Cory Maccarrone]

This change fixes 8-bit transfers and RX-only transfers.  The
SPI100k framework requires minimum 16-bit words to be written, so 8-bit
transfers must be shited by 8 bits and sent out as a 16-bit word.

Additionally, receive-only transfers were failing due to the
perceived need to fill the TX buffer with something.  This is in
fact not needed.

Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
---
 drivers/spi/omap_spi_100k.c |   23 ++++++++++++-----------
 1 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/omap_spi_100k.c b/drivers/spi/omap_spi_100k.c
index 24668b3..9bd1c92 100644
--- a/drivers/spi/omap_spi_100k.c
+++ b/drivers/spi/omap_spi_100k.c
@@ -141,7 +141,12 @@ static void spi100k_write_data(struct spi_master *master, int len, int data)
 {
 	struct omap1_spi100k *spi100k = spi_master_get_devdata(master);
 
-	/* write 16-bit word */
+	/* write 16-bit word, shifting 8-bit data if necessary */
+	if (len <= 8) {
+		data <<= 8;
+		len = 16;
+	}
+
 	spi100k_enable_clock(master);
 	writew( data , spi100k->base + SPI_TX_MSB);
 
@@ -162,6 +167,10 @@ static int spi100k_read_data(struct spi_master *master, int len)
 	int dataH,dataL;
 	struct omap1_spi100k *spi100k = spi_master_get_devdata(master);
 
+	/* Always do at least 16 bits */
+	if (len <= 8)
+		len = 16;
+
 	spi100k_enable_clock(master);
 	writew(SPI_CTRL_SEN(0) |
 	       SPI_CTRL_WORD_SIZE(len) |
@@ -214,10 +223,6 @@ omap1_spi100k_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
 	c = count;
 	word_len = cs->word_len;
 
-	/* RX_ONLY mode needs dummy data in TX reg */
-	if (xfer->tx_buf == NULL)
-		spi100k_write_data(spi->master,word_len, 0);
-
 	if (word_len <= 8) {
 		u8              *rx;
 		const u8        *tx;
@@ -227,9 +232,9 @@ omap1_spi100k_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
 		do {
 			c-=1;
 			if (xfer->tx_buf != NULL)
-				spi100k_write_data(spi->master,word_len, *tx);
+				spi100k_write_data(spi->master, word_len, *tx++);
 			if (xfer->rx_buf != NULL)
-				*rx = spi100k_read_data(spi->master,word_len);
+				*rx++ = spi100k_read_data(spi->master, word_len);
 		} while(c);
 	} else if (word_len <= 16) {
 		u16             *rx;
@@ -380,10 +385,6 @@ static void omap1_spi100k_work(struct work_struct *work)
 			if (t->len) {
 				unsigned count;
 
-				/* RX_ONLY mode needs dummy data in TX reg */
-				if (t->tx_buf == NULL)
-					spi100k_write_data(spi->master, 8, 0);
-
 				count = omap1_spi100k_txrx_pio(spi, t);
 				m->actual_length += count;
 
-- 
1.7.0.4

Re: [PATCH] [SPI] SPI100k: Fix 8-bit and RX-only transfers

[Cory Maccarrone]

On Sat, May 29, 2010 at 6:12 PM, Cory Maccarrone <darkstar6262@gmail.com> wrote:
> This change fixes 8-bit transfers and RX-only transfers.  The
> SPI100k framework requires minimum 16-bit words to be written, so 8-bit
> transfers must be shited by 8 bits and sent out as a 16-bit word.
>
> Additionally, receive-only transfers were failing due to the
> perceived need to fill the TX buffer with something.  This is in
> fact not needed.
>
> Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
> ---
>  drivers/spi/omap_spi_100k.c |   23 ++++++++++++-----------
>  1 files changed, 12 insertions(+), 11 deletions(-)
>

Any feedback on this?  I submitted it almost two months ago and
nothing seems to have happened with it.  Can this be included in the
next RC?

- Cory
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Re: [PATCH] [SPI] SPI100k: Fix 8-bit and RX-only transfers

[Cory Maccarrone]

On Sat, May 29, 2010 at 5:12 PM, Cory Maccarrone <darkstar6262@gmail.com> wrote:
> This change fixes 8-bit transfers and RX-only transfers.  The
> SPI100k framework requires minimum 16-bit words to be written, so 8-bit
> transfers must be shited by 8 bits and sent out as a 16-bit word.
>
> Additionally, receive-only transfers were failing due to the
> perceived need to fill the TX buffer with something.  This is in
> fact not needed.
>
> Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
> ---
>  drivers/spi/omap_spi_100k.c |   23 ++++++++++++-----------
>  1 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/spi/omap_spi_100k.c b/drivers/spi/omap_spi_100k.c
> index 24668b3..9bd1c92 100644
> --- a/drivers/spi/omap_spi_100k.c
> +++ b/drivers/spi/omap_spi_100k.c
> @@ -141,7 +141,12 @@ static void spi100k_write_data(struct spi_master *master, int len, int data)
>  {
>        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);
>
> -       /* write 16-bit word */
> +       /* write 16-bit word, shifting 8-bit data if necessary */
> +       if (len <= 8) {
> +               data <<= 8;
> +               len = 16;
> +       }
> +
>        spi100k_enable_clock(master);
>        writew( data , spi100k->base + SPI_TX_MSB);
>
> @@ -162,6 +167,10 @@ static int spi100k_read_data(struct spi_master *master, int len)
>        int dataH,dataL;
>        struct omap1_spi100k *spi100k = spi_master_get_devdata(master);
>
> +       /* Always do at least 16 bits */
> +       if (len <= 8)
> +               len = 16;
> +
>        spi100k_enable_clock(master);
>        writew(SPI_CTRL_SEN(0) |
>               SPI_CTRL_WORD_SIZE(len) |
> @@ -214,10 +223,6 @@ omap1_spi100k_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
>        c = count;
>        word_len = cs->word_len;
>
> -       /* RX_ONLY mode needs dummy data in TX reg */
> -       if (xfer->tx_buf == NULL)
> -               spi100k_write_data(spi->master,word_len, 0);
> -
>        if (word_len <= 8) {
>                u8              *rx;
>                const u8        *tx;
> @@ -227,9 +232,9 @@ omap1_spi100k_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
>                do {
>                        c-=1;
>                        if (xfer->tx_buf != NULL)
> -                               spi100k_write_data(spi->master,word_len, *tx);
> +                               spi100k_write_data(spi->master, word_len, *tx++);
>                        if (xfer->rx_buf != NULL)
> -                               *rx = spi100k_read_data(spi->master,word_len);
> +                               *rx++ = spi100k_read_data(spi->master, word_len);
>                } while(c);
>        } else if (word_len <= 16) {
>                u16             *rx;
> @@ -380,10 +385,6 @@ static void omap1_spi100k_work(struct work_struct *work)
>                        if (t->len) {
>                                unsigned count;
>
> -                               /* RX_ONLY mode needs dummy data in TX reg */
> -                               if (t->tx_buf == NULL)
> -                                       spi100k_write_data(spi->master, 8, 0);
> -
>                                count = omap1_spi100k_txrx_pio(spi, t);
>                                m->actual_length += count;
>
> --
> 1.7.0.4
>
>

Adding another name to the list.

- Cory

Re: [PATCH] [SPI] SPI100k: Fix 8-bit and RX-only transfers

[Grant Likely]

On Mon, Aug 2, 2010 at 9:34 AM, Cory Maccarrone <darkstar6262@gmail.com> wrote:
> On Sat, May 29, 2010 at 5:12 PM, Cory Maccarrone <darkstar6262@gmail.com> wrote:
>> This change fixes 8-bit transfers and RX-only transfers.  The
>> SPI100k framework requires minimum 16-bit words to be written, so 8-bit
>> transfers must be shited by 8 bits and sent out as a 16-bit word.
>>
>> Additionally, receive-only transfers were failing due to the
>> perceived need to fill the TX buffer with something.  This is in
>> fact not needed.
>>
>> Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
>> ---
>>  drivers/spi/omap_spi_100k.c |   23 ++++++++++++-----------
>>  1 files changed, 12 insertions(+), 11 deletions(-)
>>[...]
>
> Adding another name to the list.

This patch has been in my next-spi branch for a while, and I have a
pull request pending out to Linus.

g.

-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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