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From: William Zhang <william.zhang@broadcom.com>
To: Mark Brown <broonie@kernel.org>
Cc: Linux SPI List <linux-spi@vger.kernel.org>,
	Broadcom Kernel List <bcm-kernel-feedback-list@broadcom.com>,
	anand.gore@broadcom.com, tomer.yacoby@broadcom.com,
	dan.beygelman@broadcom.com, joel.peshkin@broadcom.com,
	f.fainelli@gmail.com, jonas.gorski@gmail.com,
	kursad.oney@broadcom.com, dregan@mail.com,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 14/16] spi: bcm63xx-hsspi: prepend: Disable spi mem dual io read op support
Date: Fri, 6 Jan 2023 19:57:15 -0800	[thread overview]
Message-ID: <1719d289-ae1a-708e-ffd7-889007465b4e@broadcom.com> (raw)
In-Reply-To: <Y7ibpEw8UKKwBksD@sirena.org.uk>

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On 01/06/2023 02:07 PM, Mark Brown wrote:
> On Fri, Jan 06, 2023 at 12:08:06PM -0800, William Zhang wrote:
>> In general the controller supports SPI dual mode operation but the
>> particular SPI flash dual io read op switches from single mode in cmd
>> phase to dual mode in address and data phase. This is not compatible
>> with prepend operation where cmd and address are sent out through the
>> prepend buffer and they must use same the number of io pins.
>>
>> This patch disables these SPI flash dual io read ops through the mem_ops
>> supports_op interface when prepend mode is used. This makes sure the SPI
>> flash driver selects the compatible read ops at run time.
> 
> This suggests that your prepend mode is attempting to combine
> incompatible transfers doesn't it?  Presumably other devices could
> generate similar access patterns...
> 
As far as I can see, only spi mem op has such pattern but agree it is 
possible that other device can generate such usage. I can add a check 
for this condition(all the prepend data must use same io width) so error 
can be printed and user can switch to dummy cs workaround.

Thank you for your feedbacks so far and have a nice weekend!

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  reply	other threads:[~2023-01-07  3:57 UTC|newest]

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-06 20:07 [PATCH 00/16] spi: bcm63xx-hsspi: driver and doc updates William Zhang
2023-01-06 20:07 ` [PATCH 01/16] dt-bindings: spi: Convert bcm63xx-hsspi bindings to json-schema William Zhang
2023-01-07 15:18   ` Rob Herring
2023-01-07 15:32   ` Krzysztof Kozlowski
2023-01-09  7:52     ` William Zhang
2023-01-09  8:48       ` Krzysztof Kozlowski
2023-01-06 20:07 ` [PATCH 02/16] dt-bindings: spi: Add bcmbca-hsspi controller support William Zhang
2023-01-08 14:51   ` Krzysztof Kozlowski
2023-01-09  8:27     ` William Zhang
2023-01-09  8:56       ` Krzysztof Kozlowski
2023-01-09 19:13         ` William Zhang
2023-01-10  8:40           ` Krzysztof Kozlowski
2023-01-10 22:18             ` Florian Fainelli
2023-01-11  1:08               ` William Zhang
2023-01-11  9:02               ` Krzysztof Kozlowski
2023-01-11 18:04                 ` William Zhang
2023-01-11 18:12                   ` Krzysztof Kozlowski
2023-01-11 18:44                     ` William Zhang
2023-01-12  8:21                       ` Krzysztof Kozlowski
2023-01-12 19:50                         ` William Zhang
2023-01-13  7:41                           ` Krzysztof Kozlowski
2023-01-14  3:17                             ` William Zhang
2023-01-15 14:31                               ` Krzysztof Kozlowski
2023-01-11  0:59             ` William Zhang
2023-01-11  9:01               ` Krzysztof Kozlowski
2023-01-06 20:07 ` [PATCH 03/16] dt-bindings: spi: Add spi peripheral specific property William Zhang
2023-01-06 21:14   ` Mark Brown
2023-01-07  3:27     ` William Zhang
2023-01-07 15:38       ` Rob Herring
2023-01-09  8:06         ` William Zhang
2023-01-09 19:19           ` Mark Brown
2023-01-09 20:18             ` William Zhang
2023-01-10 22:01               ` Mark Brown
2023-01-11 19:48                 ` William Zhang
2023-01-08 14:52   ` Krzysztof Kozlowski
2023-01-09  8:27     ` William Zhang
2023-01-06 20:07 ` [PATCH 04/16] ARM: dts: broadcom: bcmbca: Add spi controller node William Zhang
2023-01-06 20:07 ` [PATCH 05/16] arm64: " William Zhang
2023-01-06 20:07 ` [PATCH 06/16] spi: bcm63xx-hsspi: Endianness fix for ARM based SoC William Zhang
2023-01-07  7:44   ` kernel test robot
2023-01-07 21:21   ` kernel test robot
2023-01-07 21:52   ` kernel test robot
2023-01-07 23:23   ` kernel test robot
2023-01-11  6:33   ` kernel test robot
2023-01-06 20:07 ` [PATCH 07/16] spi: bcm63xx-hsspi: Add polling mode support William Zhang
2023-01-06 21:47   ` Mark Brown
2023-01-07  3:35     ` William Zhang
2023-01-09 19:06       ` Mark Brown
2023-01-09 20:10         ` William Zhang
2023-01-10 22:49           ` Mark Brown
2023-01-11 20:13             ` William Zhang
2023-01-11 22:41               ` Mark Brown
2023-01-11 22:57                 ` William Zhang
2023-01-06 20:08 ` [PATCH 08/16] spi: bcm63xx-hsspi: Handle cs_change correctly William Zhang
2023-01-06 20:08 ` [PATCH 09/16] spi: bcm63xx-hsspi: Fix multi-bit mode setting William Zhang
2023-01-06 20:08 ` [PATCH 10/16] spi: bcm63xx-hsspi: Make dummy cs workaround as an option William Zhang
2023-01-12 18:08   ` Mark Brown
2023-01-18 23:09     ` William Zhang
2023-01-19 13:09       ` Mark Brown
2023-01-06 20:08 ` [PATCH 11/16] spi: bcm63xx-hsspi: Add prepend feature support William Zhang
2023-01-06 22:00   ` Mark Brown
2023-01-07  3:52     ` William Zhang
2023-01-09 19:31       ` Mark Brown
2023-01-09 20:43         ` William Zhang
2023-01-10 21:18           ` Mark Brown
2023-01-11 19:42             ` William Zhang
2023-01-12 16:57               ` Mark Brown
2023-01-06 20:08 ` [PATCH 12/16] spi: bcm63xx-hsspi: Add clock gate disable option support William Zhang
2023-01-06 20:08 ` [PATCH 13/16] spi: spi-mem: Allow controller supporting mem_ops without exec_op William Zhang
2023-01-06 20:08 ` [PATCH 14/16] spi: bcm63xx-hsspi: prepend: Disable spi mem dual io read op support William Zhang
2023-01-06 22:07   ` Mark Brown
2023-01-07  3:57     ` William Zhang [this message]
2023-01-06 20:08 ` [PATCH 15/16] spi: bcmbca-hsspi: Add driver for newer HSSPI controller William Zhang
2023-01-07 22:02   ` kernel test robot
2023-01-08  2:25   ` kernel test robot
2023-01-06 20:08 ` [PATCH 16/16] MAINTAINERS: Add entry for Broadcom Broadband SoC HS SPI drivers William Zhang

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