From: Pavel Machek <pavel@ucw.cz>
To: Lubomir Rintel <lkundrak@v3.sk>
Cc: Mark Brown <broonie@kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
James Cameron <quozl@laptop.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Eric Miao <eric.y.miao@gmail.com>,
Haojian Zhuang <haojian.zhuang@gmail.com>,
Daniel Mack <daniel@zonque.org>,
Robert Jarzmik <robert.jarzmik@free.fr>,
linux-spi@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 11/11] spi: pxa2xx: Deal with the leftover garbage in TXFIFO
Date: Sun, 4 Nov 2018 13:19:01 +0100 [thread overview]
Message-ID: <20181104121901.GW23864@amd> (raw)
In-Reply-To: <20181010170936.316862-12-lkundrak@v3.sk>
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On Wed 2018-10-10 19:09:36, Lubomir Rintel wrote:
> There doesn't seem to be a way to empty TXFIFO on MMP2. The datasheet is
> super-secret and the method described in Armada 16x manual won't work:
>
> "The TXFIFO and RXFIFO are cleared to 0b0 when the SSPx port is reset or
> disabled (by writing a 0b0 to the <Synchronous Serial Port Enable> field
> in the SSP Control Register 0)."
>
> # devmem 0xd4037008 # read SSSR
> 0x0000F204
> # devmem 0xd4037000 32 0x80 # SSE off in SSCR0
> # devmem 0xd4037000 32 0x87 # SSE on
> # devmem 0xd4037008
> 0x0000F204
> ^ TXFIFO level is still 2. Sigh.
>
> The OLPC 1.75 boot firmware leaves two bytes in the TXFIFO. Those are
> basically throwaway bytes used in response to the messages from the EC.
> The OLPC kernel copes with this by power-cycling the hardware. Perhaps
> the firmware should do this instead.
>
> Other than that, there's not much we can do other than complain loudly
> until the garbage gets drained and discard the actual data... For the
> OLPC EC this will work just fine and pushing more data to TXFIFO would
> break further transactions.
>
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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From: pavel@ucw.cz (Pavel Machek)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 11/11] spi: pxa2xx: Deal with the leftover garbage in TXFIFO
Date: Sun, 4 Nov 2018 13:19:01 +0100 [thread overview]
Message-ID: <20181104121901.GW23864@amd> (raw)
In-Reply-To: <20181010170936.316862-12-lkundrak@v3.sk>
On Wed 2018-10-10 19:09:36, Lubomir Rintel wrote:
> There doesn't seem to be a way to empty TXFIFO on MMP2. The datasheet is
> super-secret and the method described in Armada 16x manual won't work:
>
> "The TXFIFO and RXFIFO are cleared to 0b0 when the SSPx port is reset or
> disabled (by writing a 0b0 to the <Synchronous Serial Port Enable> field
> in the SSP Control Register 0)."
>
> # devmem 0xd4037008 # read SSSR
> 0x0000F204
> # devmem 0xd4037000 32 0x80 # SSE off in SSCR0
> # devmem 0xd4037000 32 0x87 # SSE on
> # devmem 0xd4037008
> 0x0000F204
> ^ TXFIFO level is still 2. Sigh.
>
> The OLPC 1.75 boot firmware leaves two bytes in the TXFIFO. Those are
> basically throwaway bytes used in response to the messages from the EC.
> The OLPC kernel copes with this by power-cycling the hardware. Perhaps
> the firmware should do this instead.
>
> Other than that, there's not much we can do other than complain loudly
> until the garbage gets drained and discard the actual data... For the
> OLPC EC this will work just fine and pushing more data to TXFIFO would
> break further transactions.
>
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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next prev parent reply other threads:[~2018-11-04 12:19 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-10 17:09 [PATCH 0/11] spi: pxa2xx: add DT and slave mode support Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-10-10 17:09 ` [PATCH v2 01/11] dt-bindings: spi/spi-pxa2xx: add PXA2xx SSP SPI Controller Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-10-11 14:27 ` Mark Brown
2018-10-11 14:27 ` Mark Brown
2018-10-11 17:59 ` Lubomir Rintel
2018-10-11 17:59 ` Lubomir Rintel
2018-10-12 17:00 ` Mark Brown
2018-10-12 17:00 ` Mark Brown
2018-10-17 19:32 ` Rob Herring
2018-10-17 19:32 ` Rob Herring
2018-11-04 12:00 ` Pavel Machek
2018-11-04 12:00 ` Pavel Machek
2018-10-10 17:09 ` [PATCH v2 02/11] PCI: Provide pci_match_id() with CONFIG_PCI=n Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-11-04 12:02 ` Pavel Machek
2018-11-04 12:02 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 03/11] spi: pxa2xx: Use an enum for type Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-11-04 12:03 ` Pavel Machek
2018-11-04 12:03 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 04/11] spi: pxa2xx: Add devicetree support Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-11-04 12:04 ` Pavel Machek
2018-11-04 12:04 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 05/11] DT: marvell,mmp2: Add SSP1 and SSP3 Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-10-29 5:35 ` James Cameron
2018-10-29 5:35 ` James Cameron
2018-11-04 12:06 ` Pavel Machek
2018-11-04 12:06 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 06/11] dt-bindings: spi/spi-pxa2xx: Add spi-slave property Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-10-17 19:33 ` Rob Herring
2018-10-17 19:33 ` Rob Herring
2018-11-04 12:07 ` Pavel Machek
2018-11-04 12:07 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 07/11] spi: Deal with slaves that return from transfer_one() unfinished Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-10-11 7:23 ` Geert Uytterhoeven
2018-10-11 7:23 ` Geert Uytterhoeven
2018-11-04 12:09 ` Pavel Machek
2018-11-04 12:09 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 08/11] spi: pxa2xx: Add slave mode support Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-11-04 12:12 ` Pavel Machek
2018-11-04 12:12 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 09/11] dt-bindings: spi/spi-pxa2xx: Add ready GPIO signal Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-10-11 7:26 ` Geert Uytterhoeven
2018-10-11 7:26 ` Geert Uytterhoeven
2018-11-04 12:13 ` Pavel Machek
2018-11-04 12:13 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 10/11] spi: pxa2xx: Add ready signal Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-10-11 7:28 ` Geert Uytterhoeven
2018-10-11 7:28 ` Geert Uytterhoeven
2018-10-11 16:13 ` Lubomir Rintel
2018-10-11 16:13 ` Lubomir Rintel
2018-11-04 12:16 ` Pavel Machek
2018-11-04 12:16 ` Pavel Machek
2018-10-10 17:09 ` [PATCH 11/11] spi: pxa2xx: Deal with the leftover garbage in TXFIFO Lubomir Rintel
2018-10-10 17:09 ` Lubomir Rintel
2018-11-04 12:19 ` Pavel Machek [this message]
2018-11-04 12:19 ` Pavel Machek
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