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SubjectRE: Re: [PATCH] spi: imx: add a check for speed_hz before calculating the clock
Date

> -----Original Message-----
> From: Mark Brown <broonie@kernel.org>
> Sent: Thursday, April 8, 2021 21:44
> To: Clark Wang <xiaoning.wang@nxp.com>
> Cc: shawnguo@kernel.org; s.hauer@pengutronix.de; festevam@gmail.com;
> kernel@pengutronix.de; dl-linux-imx <linux-imx@nxp.com>; linux-
> spi@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> kernel@vger.kernel.org
> Subject: [EXT] Re: [PATCH] spi: imx: add a check for speed_hz before
calculating
> the clock
>
> On Thu, Apr 08, 2021 at 06:33:47PM +0800, Clark Wang wrote:
> > When some drivers use spi to send data, spi_transfer->speed_hz is not
> > assigned. If spidev->max_speed_hz is not assigned as well, it will
> > cause an error in configuring the clock.
>
> > Add a check for these two values before configuring the clock. An
> > error will be returned when they are not assigned.
>
> For the case where the transfer speed is not set __spi_validate() will
take the
> controller's maximum speed so the controller should just be able to
> unconditionally use the transfer's speed. Your issue is therefore that
the
> controllers are sometimes not setting a maximum speed which this doesn't
seem
> to fix AFAICT? I'd expect the driver to be able to work one out based on
the
> input clock.

Hi Mark,

Yes, you are right. If the t->speed_hz is not provided, it will use
spi->max_speed_hz.
This patch is not needed.
The issue I met is that t->speed_hz is not provided in slave mode. But this
is normal in slave mode.
The problem is spi-imx should not config the clock divider in slave mode. I
will send a new patch to disable the clock configuration in slave mode
later.

However, I notice that you have applied this patch to the next branch?
Will you revert this patch?
I think you may want to apply this patch I sent before.

Author: Clark Wang <xiaoning.wang@nxp.com>
Date: Mon Dec 14 17:05:04 2020 +0800

spi: imx: add 16/32 bits per word support for slave mode

Enable 16/32 bits per word support for spi-imx slave mode.
It only support 8 bits per word in slave mode before.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Reviewed-by: Haibo Chen <haibo.chen@nxp.com>

Thank you very much! :)

Best Regards,
Clark Wang

>
> > struct spi_imx_devtype_data {
> > void (*intctrl)(struct spi_imx_data *, int);
> > int (*prepare_message)(struct spi_imx_data *, struct spi_message *);
> > - int (*prepare_transfer)(struct spi_imx_data *, struct spi_device *,
> > - struct spi_transfer *);
> > + int (*prepare_transfer)(struct spi_imx_data *, struct spi_device *);
> > void (*trigger)(struct spi_imx_data *);
> > int (*rx_available)(struct spi_imx_data *);
> > void (*reset)(struct spi_imx_data *);
>
> This seems to be a fairly big and surprising refactoring for the described
change.
> It's quite hard to tie the change to the changelog.
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