Re: [RFC PATCH 4/6] spi: ti-qspi: Implement the spi_mem interface

Vignesh R
2018-02-12T16:00:42Z

On 12-Feb-18 6:01 PM, Boris Brezillon wrote:
> On Mon, 12 Feb 2018 17:13:55 +0530
> Vignesh R <vigneshr@ti.com> wrote:
>
>> On Tuesday 06 February 2018 04:51 AM, Boris Brezillon wrote:
>> > From: Boris Brezillon <boris.brezillon@free-electrons.com>
>> >
>> > The spi_mem interface is meant to replace the spi_flash_read() one.
>> > Implement the ->exec_op() method so that we can smoothly get rid of the
>> > old interface.
>> >
>> > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
>> > ---
>> >  drivers/spi/spi-ti-qspi.c | 85 +++++++++++++++++++++++++++++++++++++++--------
>> >  1 file changed, 72 insertions(+), 13 deletions(-)
>> >
>> > diff --git a/drivers/spi/spi-ti-qspi.c b/drivers/spi/spi-ti-qspi.c
>> > index c24d9b45a27c..40cac3ef6cc9 100644
>> > --- a/drivers/spi/spi-ti-qspi.c
>> > +++ b/drivers/spi/spi-ti-qspi.c
>>
>> [...]
>>
>> > +static const struct spi_controller_mem_ops ti_qspi_mem_ops = {
>> > +   .exec_op = ti_qspi_exec_mem_op,
>>
>>        .supports_op = ti_qspi_supports_mem_op,
>>
>> Its required as per spi_controller_check_ops() in Patch 1/6
>
> ->supports_op() is optional, and if it's missing, the core will do the
> regular QuadSPI/DualSPI/SingleSPI check (see spi_mem_supports_op()
> implementation).

You might have overlooked spi_controller_check_ops() from Patch 1/6:
+static int spi_controller_check_ops(struct spi_controller *ctlr)
+{
+ /*
+ * The controller can implement only the high-level SPI-memory
+ * operations if it does not support regular SPI transfers.
+ */
+ if (ctlr->mem_ops) {
+ if (!ctlr->mem_ops->supports_op ||
+ !ctlr->mem_ops->exec_op)
+ return -EINVAL;
+ } else if (!ctlr->transfer && !ctlr->transfer_one &&
+ !ctlr->transfer_one_message) {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+

So if ->supports_op() is not populated by SPI controller driver, then
driver probe fails with -EINVAL. This is what I observed on my TI
hardware when testing this patch series.

> This being said, if you think a custom ->supports_op()
> implementation is needed for this controller I can add one.
>

spi_mem_supports_op() should suffice for now if above issue is fixed.

Regards
Vignesh