[lkml]   [2018]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 1/2] dt-bindings: spi: dw: add cs-override property
On Wed, 2018-10-10 at 10:08 +0300, Talel Shenhar wrote:
> The dw spi controller has an auto-deselect of Chip-Select, in case there is
> no data inside the Tx FIFO. While working on platforms with Alpine chips,
> auto-deselect mode causes an issue for some spi devices that can't handle
> the Chip-Select deselect in the middle of a transaction. It is a normal
> behavior for a Tx FIFO to be empty in the middle of a transaction, due to

So that's the problem! I, like everyone else I suspect, switched to
using GPIO chip selects with this driver because of this. I narrowed
it down to a CS de-assert when the bus switched from TX to RX, which of
course makes a SPI register read fail on most devices. The TX FIFO
would empty at this point, so that would explain it.

Did the designers of this IP ever read a SPI device datasheet???

Got to agree with Mark Brown, why would anyone ever want to NOT have it
work properly? The previous behavior is not "alternate correct", it's
 \ /
  Last update: 2018-10-11 00:23    [W:0.165 / U:4.740 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site