RE: [PATCH] (re-send) spi-imx: improve timing of bursts

[Daniel Sobe <daniel.sobe@xxxxxxx>]

Hi Mark,

thanks for your reply and your comments. I will make sure to follow your suggestions next time I try to submit a patch to the mailing list. It doesn't make sense to try again with this patch, because the project in which context it was created is already closed.

Regards,

Daniel

Daniel Sobe
Engineer, BL Car
NXP Semiconductors Germany GmbH

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________________________________________
From: Mark Brown <broonie@xxxxxxxxxx>
Sent: Saturday, August 16, 2014 5:13 PM
To: Daniel Sobe
Cc: linux-spi@xxxxxxxxxxxxxxx
Subject: Re: [PATCH] (re-send) spi-imx: improve timing of bursts

On Fri, Mar 28, 2014 at 11:05:49AM +0000, Daniel Sobe wrote:
>
> Hi,
>
> The patch below addresses 2 improvements:

Please follow the patch submission process covered in SubmittingPatches
- in particular you need to send patches to the relevant developers as
well as the mailing lists, you need to format your changelogs in the
standard Linux style (including word wrapping within paragraphs) and you
need to follow the kernel coding style.

If you only send your patch to the list there's a good chance it'll be
missed.

> 1) Burstsize of a transfer adjusted up to the maximum burstsize of the  hardware --> no unwanted CS toggling between data words
> 2) Variable trigger level allows to increase priority for data transfer,  enables continuous transfers up to the burstsize. --> remove gaps  every 64 words

> The original behaviour of the driver is untouched. The additional features can be enabled via sysfs.

Why would you ever want /CS toggling between words - such behaviour is
just plain buggy?

> +// (sysfs-)tunable attributes
> +static int allow_big_bursts = 0; // if set to 1 this enables 32-bit big bursts
> +static int tx_fifo_thres = -1;   // if positive, use TX data request interrupt when applicable

These would need to be per device rather than global.  It's also not
clear to me that we don't want to enable some level of FIFO threashold
usage by default, perhaps aiming for something just slightly below the
full FIFO so that we minimise the number of extra interrupts but
increase throughput on lightly loaded systems - I'm not even sure that
making this behaviour tunable is needed.
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