Re: [PATCH 2/3] i2c-axxia: check for error conditions first

Sverdlin, Alexander (Nokia - DE/Ulm)
2018-12-11T12:02:32Z

Hi!

On 10/12/2018 16:01, Adamski, Krzysztof (Nokia - PL/Wroclaw) wrote:
> It was observed that when using seqentional mode contrary to the
^^^^^^^^^^^
> documentation, the SS bit (which is supposed to only be set if
> automatic/sequence command completed normally), is sometimes set
> together with NA (NAK in address phase) causing transfer to falsely be
> considered successful.
>
> My assumption is that this does not happen during manual mode since the
> controller is stopping its work the moment it sets NA/ND bit in status
> register. This is not the case in Automatic/Sequentional mode where it
^^^^^^^^^^^^
> is still working to send STOP condition and the actual status we get
> depends on the time when the ISR is run.
>
> This patch changes the order of checking status bits in ISR - error
> conditions are checked first and only if none of them occurred, the
> transfer may be considered successful. This is required to introduce
> using of sequentional mode in next patch.
^^^^^^^^^^^^
sequential

Reviewed-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>

> Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
> ---
> drivers/i2c/busses/i2c-axxia.c | 32 ++++++++++++++++----------------
> 1 file changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-axxia.c b/drivers/i2c/busses/i2c-axxia.c
> index d37caf694fbf..35258321e81b 100644
> --- a/drivers/i2c/busses/i2c-axxia.c
> +++ b/drivers/i2c/busses/i2c-axxia.c
> @@ -296,22 +296,7 @@ static irqreturn_t axxia_i2c_isr(int irq, void *_dev)
> i2c_int_disable(idev, MST_STATUS_TFL);
> }
>
> - if (status & MST_STATUS_SCC) {
> - /* Stop completed */
> - i2c_int_disable(idev, ~MST_STATUS_TSS);
> - complete(&idev->msg_complete);
> - } else if (status & MST_STATUS_SNS) {
> - /* Transfer done */
> - i2c_int_disable(idev, ~MST_STATUS_TSS);
> - if (i2c_m_rd(idev->msg) && idev->msg_xfrd < idev->msg->len)
> - axxia_i2c_empty_rx_fifo(idev);
> - complete(&idev->msg_complete);
> - } else if (status & MST_STATUS_TSS) {
> - /* Transfer timeout */
> - idev->msg_err = -ETIMEDOUT;
> - i2c_int_disable(idev, ~MST_STATUS_TSS);
> - complete(&idev->msg_complete);
> - } else if (unlikely(status & MST_STATUS_ERR)) {
> + if (unlikely(status & MST_STATUS_ERR)) {
> /* Transfer error */
> i2c_int_disable(idev, ~0);
> if (status & MST_STATUS_AL)
> @@ -328,6 +313,21 @@ static irqreturn_t axxia_i2c_isr(int irq, void *_dev)
> readl(idev->base + MST_TX_BYTES_XFRD),
> readl(idev->base + MST_TX_XFER));
> complete(&idev->msg_complete);
> + } else if (status & MST_STATUS_SCC) {
> + /* Stop completed */
> + i2c_int_disable(idev, ~MST_STATUS_TSS);
> + complete(&idev->msg_complete);
> + } else if (status & MST_STATUS_SNS) {
> + /* Transfer done */
> + i2c_int_disable(idev, ~MST_STATUS_TSS);
> + if (i2c_m_rd(idev->msg) && idev->msg_xfrd < idev->msg->len)
> + axxia_i2c_empty_rx_fifo(idev);
> + complete(&idev->msg_complete);
> + } else if (status & MST_STATUS_TSS) {
> + /* Transfer timeout */
> + idev->msg_err = -ETIMEDOUT;
> + i2c_int_disable(idev, ~MST_STATUS_TSS);
> + complete(&idev->msg_complete);
> }
>
> out:
>

--
Best regards,
Alexander Sverdlin.