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From: David Lechner <david@lechnology.com>
To: Vignesh R <vigneshr@ti.com>,
	"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>
Cc: Mark Brown <broonie@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-omap@vger.kernel.org" <linux-omap@vger.kernel.org>
Subject: Re: [PATCH] Revert "spi: omap2-mcspi: Set FIFO DMA trigger level to word length"
Date: Mon, 14 Jan 2019 17:50:34 -0600	[thread overview]
Message-ID: <bb7e13ee-f6ed-a619-c56e-53aad91a1432@lechnology.com> (raw)
In-Reply-To: <829bdc72-cf96-6aee-28d8-a47d0430710d@ti.com>

On 1/14/19 6:30 AM, Vignesh R wrote:
> 
> 
> On 14/01/19 2:19 AM, David Lechner wrote:
>> This reverts commit b682cffa3ac6d9d9e16e9b413c45caee3b391fab.
>>
>> That commit breaks displays using tinydrm drivers, such as ili9225.
>>
>> It causes corruption in the image that is displayed (it looks like only
>> 1/2 of the framebuffer data is sent, the other half of the display
>> remains blank.)
>>
>> The following error appears multiple times:
>>
>>      ili9225 spi1.0: EOW timed out
>>
>> Eventually, the system locks up without any additional errors.
>>
> 
> Oops, that's unfortunate. I see ili9225 is using bits_per_word = 16.
> I believe commit b682cffa3ac6d9d broke spi_transfers where
> bits_per_word anything other than 8 bits.
> I don't have ili9225 HW but was able emulate this condition using a SPI
> flash as slave on AM335x and successfully reproduced the issue. Could
> you test if this diff[1] helps in fixing the regression without needing
> to revert commit b682cffa3ac6d9d?

Yes, this changes fixes the problem. Thanks!

> 
> If below diff does not help, then could you post logs of types of
> spi_transfers being queued by ili9225 driver? I guess you can dump them
> by enabling DEBUG option in tinydrm-helpers.c.
> Also which TI SoC are you using?
> 
I'm using BeagleBone Green, so AM335x as well.

  reply	other threads:[~2019-01-14 23:50 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-13 20:49 [PATCH] Revert "spi: omap2-mcspi: Set FIFO DMA trigger level to word length" David Lechner
2019-01-13 20:52 ` David Lechner
2019-01-14 12:30 ` Vignesh R
2019-01-14 23:50   ` David Lechner [this message]
2019-01-15  0:07     ` Mark Brown
2019-01-14 23:57   ` David Lechner

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