RE: [PATCH V5 09/15] spi: Add stacked and parallel memories support in SPI core - Mahapatra, Amit Kumar via Alsa-devel

From: "Mahapatra, Amit Kumar via Alsa-devel" <alsa-devel@alsa-project.org>
To: Jonas Gorski <jonas.gorski@gmail.com>
Cc: "broonie@kernel.org" <broonie@kernel.org>,
	"miquel.raynal@bootlin.com" <miquel.raynal@bootlin.com>,
	"richard@nod.at" <richard@nod.at>,
	"vigneshr@ti.com" <vigneshr@ti.com>,
	"jic23@kernel.org" <jic23@kernel.org>,
	"tudor.ambarus@microchip.com" <tudor.ambarus@microchip.com>,
	"pratyush@kernel.org" <pratyush@kernel.org>,
	"Mehta, Sanju" <Sanju.Mehta@amd.com>,
	"chin-ting_kuo@aspeedtech.com" <chin-ting_kuo@aspeedtech.com>,
	"clg@kaod.org" <clg@kaod.org>,
	"kdasu.kdev@gmail.com" <kdasu.kdev@gmail.com>,
	"f.fainelli@gmail.com" <f.fainelli@gmail.com>,
	"rjui@broadcom.com" <rjui@broadcom.com>,
	"sbranden@broadcom.com" <sbranden@broadcom.com>,
	"eajames@linux.ibm.com" <eajames@linux.ibm.com>,
	"olteanv@gmail.com" <olteanv@gmail.com>,
	"han.xu@nxp.com" <han.xu@nxp.com>,
	"john.garry@huawei.com" <john.garry@huawei.com>,
	"shawnguo@kernel.org" <shawnguo@kernel.org>,
	"s.hauer@pengutronix.de" <s.hauer@pengutronix.de>,
	"narmstrong@baylibre.com" <narmstrong@baylibre.com>,
	"khilman@baylibre.com" <khilman@baylibre.com>,
	"matthias.bgg@gmail.com" <matthias.bgg@gmail.com>,
	"haibo.chen@nxp.com" <haibo.chen@nxp.com>,
	"linus.walleij@linaro.org" <linus.walleij@linaro.org>,
	"daniel@zonque.org" <daniel@zonque.org>,
	"haojian.zhuang@gmail.com" <haojian.zhuang@gmail.com>,
	"robert.jarzmik@free.fr" <robert.jarzmik@free.fr>,
	"agross@kernel.org" <agross@kernel.org>,
	"bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
	"heiko@sntech.de" <heiko@sntech.de>,
	"krzysztof.kozlowski@linaro.org" <krzysztof.kozlowski@linaro.org>,
	"andi@etezian.org" <andi@etezian.org>,
	"mcoquelin.stm32@gmail.com" <mcoquelin.stm32@gmail.com>,
	"alexandre.torgue@foss.st.com" <alexandre.torgue@foss.st.com>,
	"wens@csie.org" <wens@csie.org>,
	"jernej.skrabec@gmail.com" <jernej.skrabec@gmail.com>,
	"samuel@sholland.org" <samuel@sholland.org>,
	"masahisa.kojima@linaro.org" <masahisa.kojima@linaro.org>,
	"jaswinder.singh@linaro.org" <jaswinder.singh@linaro.org>,
	"rostedt@goodmis.org" <rostedt@goodmis.org>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"l.stelmach@samsung.com" <l.stelmach@samsung.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"edumazet@google.com" <edumazet@google.com>,
	"kuba@kernel.org" <kuba@kernel.org>,
	"pabeni@redhat.com" <pabeni@redhat.com>,
	"alex.aring@gmail.com" <alex.aring@gmail.com>,
	"stefan@datenfreihafen.org" <stefan@datenfreihafen.org>,
	"kvalo@kernel.org" <kvalo@kernel.org>,
	"james.schulman@cirrus.com" <james.schulman@cirrus.com>,
	"david.rhodes@cirrus.com" <david.rhodes@cirrus.com>,
	"tanureal@opensource.cirrus.com" <tanureal@opensource.cirrus.com>,
	"rf@opensource.cirrus.com" <rf@opensource.cirrus.com>,
	"tiwai@suse.com" <tiwai@suse.com>,
	"npiggin@gmail.com" <npiggin@gmail.com>,
	"christophe.leroy@csgroup.eu" <christophe.leroy@csgroup.eu>,
	"mpe@ellerman.id.au" <mpe@ellerman.id.au>,
	"oss@buserror.net" <oss@buserror.net>,
	"windhl@126.com" <windhl@126.com>,
	"yangyingliang@huawei.com" <yangyingliang@huawei.com>,
	"william.zhang@broadcom.com" <william.zhang@broadcom.com>,
	"kursad.oney@broadcom.com" <kursad.oney@broadcom.com>,
	"anand.gore@broadcom.com" <anand.gore@broadcom.com>,
	"rafal@milecki.pl" <rafal@milecki.pl>,
	"git (AMD-Xilinx)" <git@amd.com>,
	"linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"joel@jms.id.au" <joel@jms.id.au>,
	"andrew@aj.id.au" <andrew@aj.id.au>,
	"radu_nicolae.pirea@upb.ro" <radu_nicolae.pirea@upb.ro>,
	"nicolas.ferre@microchip.com" <nicolas.ferre@microchip.com>,
	"alexandre.belloni@bootlin.com" <alexandre.belloni@bootlin.com>,
	"claudiu.beznea@microchip.com" <claudiu.beznea@microchip.com>,
	"bcm-kernel-feedback-list@broadcom.com"
	<bcm-kernel-feedback-list@broadcom.com>,
	"fancer.lancer@gmail.com" <fancer.lancer@gmail.com>,
	"kernel@pengutronix.de" <kernel@pengutronix.de>,
	"festevam@gmail.com" <festevam@gmail.com>,
	"linux-imx@nxp.com" <linux-imx@nxp.com>,
	"jbrunet@baylibre.com" <jbrunet@baylibre.com>,
	"martin.blumenstingl@googlemail.com"
	<martin.blumenstingl@googlemail.com>,
	"avifishman70@gmail.com" <avifishman70@gmail.com>,
	"tmaimon77@gmail.com" <tmaimon77@gmail.com>,
	"tali.perry1@gmail.com" <tali.perry1@gmail.com>,
	"venture@google.com" <venture@google.com>,
	"yuenn@google.com" <yuenn@google.com>,
	"benjaminfair@google.com" <benjaminfair@google.com>,
	"yogeshgaur.83@gmail.com" <yogeshgaur.83@gmail.com>,
	"konrad.dybcio@somainline.org" <konrad.dybcio@somainline.org>,
	"alim.akhtar@samsung.com" <alim.akhtar@samsung.com>,
	"ldewangan@nvidia.com" <ldewangan@nvidia.com>,
	"thierry.reding@gmail.com" <thierry.reding@gmail.com>,
	"jonathanh@nvidia.com" <jonathanh@nvidia.com>,
	"Simek, Michal" <michal.simek@amd.com>,
	"linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>,
	"openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	"linux-rpi-kernel@lists.infradead.org"
	<linux-rpi-kernel@lists.infradead.org>,
	"linux-amlogic@lists.infradead.org"
	<linux-amlogic@lists.infradead.org>,
	"linux-mediatek@lists.infradead.org"
	<linux-mediatek@lists.infradead.org>,
	"linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>,
	"linux-rockchip@lists.infradead.org"
	<linux-rockchip@lists.infradead.org>,
	"linux-samsung-soc@vger.kernel.org"
	<linux-samsung-soc@vger.kernel.org>,
	"linux-stm32@st-md-mailman.stormreply.com"
	<linux-stm32@st-md-mailman.stormreply.com>,
	"linux-sunxi@lists.linux.dev" <linux-sunxi@lists.linux.dev>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-wpan@vger.kernel.org" <linux-wpan@vger.kernel.org>,
	"libertas-dev@lists.infradead.org"
	<libertas-dev@lists.infradead.org>,
	"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
	"linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>,
	"lars@metafoo.de" <lars@metafoo.de>,
	"Michael.Hennerich@analog.com" <Michael.Hennerich@analog.com>,
	"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
	"michael@walle.cc" <michael@walle.cc>,
	"palmer@dabbelt.com" <palmer@dabbelt.com>,
	"linux-riscv@lists.infradead.org"
	<linux-riscv@lists.infradead.org>,
	"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
	"patches@opensource.cirrus.com" <patches@opensource.cirrus.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
	"amitrkcian2002@gmail.com" <amitrkcian2002@gmail.com>
Subject: RE: [PATCH V5 09/15] spi: Add stacked and parallel memories support in SPI core
Date: Tue, 7 Mar 2023 11:09:41 +0000	[thread overview]
Message-ID: <167820130914.26.16600062916905060066@mailman-core.alsa-project.org> (raw)
In-Reply-To: <CAOiHx=nmsAh3ADL3s0eZKpEZJqCB_POi=8YjfxrHYLEbjRfwHg@mail.gmail.com>

[-- Attachment #0: Type: message/rfc822, Size: 25285 bytes --]

From: "Mahapatra, Amit Kumar" <amit.kumar-mahapatra@amd.com>
To: Jonas Gorski <jonas.gorski@gmail.com>
Cc: "broonie@kernel.org" <broonie@kernel.org>, "miquel.raynal@bootlin.com" <miquel.raynal@bootlin.com>, "richard@nod.at" <richard@nod.at>, "vigneshr@ti.com" <vigneshr@ti.com>, "jic23@kernel.org" <jic23@kernel.org>, "tudor.ambarus@microchip.com" <tudor.ambarus@microchip.com>, "pratyush@kernel.org" <pratyush@kernel.org>, "Mehta, Sanju" <Sanju.Mehta@amd.com>, "chin-ting_kuo@aspeedtech.com" <chin-ting_kuo@aspeedtech.com>, "clg@kaod.org" <clg@kaod.org>, "kdasu.kdev@gmail.com" <kdasu.kdev@gmail.com>, "f.fainelli@gmail.com" <f.fainelli@gmail.com>, "rjui@broadcom.com" <rjui@broadcom.com>, "sbranden@broadcom.com" <sbranden@broadcom.com>, "eajames@linux.ibm.com" <eajames@linux.ibm.com>, "olteanv@gmail.com" <olteanv@gmail.com>, "han.xu@nxp.com" <han.xu@nxp.com>, "john.garry@huawei.com" <john.garry@huawei.com>, "shawnguo@kernel.org" <shawnguo@kernel.org>, "s.hauer@pengutronix.de" <s.hauer@pengutronix.de>, "narmstrong@baylibre.com" <narmstrong@baylibre.com>, "khilman@baylibre.com" <khilman@baylibre.com>, "matthias.bgg@gmail.com" <matthias.bgg@gmail.com>, "haibo.chen@nxp.com" <haibo.chen@nxp.com>, "linus.walleij@linaro.org" <linus.walleij@linaro.org>, "daniel@zonque.org" <daniel@zonque.org>, "haojian.zhuang@gmail.com" <haojian.zhuang@gmail.com>, "robert.jarzmik@free.fr" <robert.jarzmik@free.fr>, "agross@kernel.org" <agross@kernel.org>, "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>, "heiko@sntech.de" <heiko@sntech.de>, "krzysztof.kozlowski@linaro.org" <krzysztof.kozlowski@linaro.org>, "andi@etezian.org" <andi@etezian.org>, "mcoquelin.stm32@gmail.com" <mcoquelin.stm32@gmail.com>, "alexandre.torgue@foss.st.com" <alexandre.torgue@foss.st.com>, "wens@csie.org" <wens@csie.org>, "jernej.skrabec@gmail.com" <jernej.skrabec@gmail.com>, "samuel@sholland.org" <samuel@sholland.org>, "masahisa.kojima@linaro.org" <masahisa.kojima@linaro.org>, "jaswinder.singh@linaro.org" <jaswinder.singh@linaro.org>, "rostedt@goodmis.org" <rostedt@goodmis.org>, "mingo@redhat.com" <mingo@redhat.com>, "l.stelmach@samsung.com" <l.stelmach@samsung.com>, "davem@davemloft.net" <davem@davemloft.net>, "edumazet@google.com" <edumazet@google.com>, "kuba@kernel.org" <kuba@kernel.org>, "pabeni@redhat.com" <pabeni@redhat.com>, "alex.aring@gmail.com" <alex.aring@gmail.com>, "stefan@datenfreihafen.org" <stefan@datenfreihafen.org>, "kvalo@kernel.org" <kvalo@kernel.org>, "james.schulman@cirrus.com" <james.schulman@cirrus.com>, "david.rhodes@cirrus.com" <david.rhodes@cirrus.com>, "tanureal@opensource.cirrus.com" <tanureal@opensource.cirrus.com>, "rf@opensource.cirrus.com" <rf@opensource.cirrus.com>, "tiwai@suse.com" <tiwai@suse.com>, "npiggin@gmail.com" <npiggin@gmail.com>, "christophe.leroy@csgroup.eu" <christophe.leroy@csgroup.eu>, "mpe@ellerman.id.au" <mpe@ellerman.id.au>, "oss@buserror.net" <oss@buserror.net>, "windhl@126.com" <windhl@126.com>, "yangyingliang@huawei.com" <yangyingliang@huawei.com>, "william.zhang@broadcom.com" <william.zhang@broadcom.com>, "kursad.oney@broadcom.com" <kursad.oney@broadcom.com>, "anand.gore@broadcom.com" <anand.gore@broadcom.com>, "rafal@milecki.pl" <rafal@milecki.pl>, "git (AMD-Xilinx)" <git@amd.com>, "linux-spi@vger.kernel.org" <linux-spi@vger.kernel.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "joel@jms.id.au" <joel@jms.id.au>, "andrew@aj.id.au" <andrew@aj.id.au>, "radu_nicolae.pirea@upb.ro" <radu_nicolae.pirea@upb.ro>, "nicolas.ferre@microchip.com" <nicolas.ferre@microchip.com>, "alexandre.belloni@bootlin.com" <alexandre.belloni@bootlin.com>, "claudiu.beznea@microchip.com" <claudiu.beznea@microchip.com>, "bcm-kernel-feedback-list@broadcom.com" <bcm-kernel-feedback-list@broadcom.com>, "fancer.lancer@gmail.com" <fancer.lancer@gmail.com>, "kernel@pengutronix.de" <kernel@pengutronix.de>, "festevam@gmail.com" <festevam@gmail.com>, "linux-imx@nxp.com" <linux-imx@nxp.com>, "jbrunet@baylibre.com" <jbrunet@baylibre.com>, "martin.blumenstingl@googlemail.com" <martin.blumenstingl@googlemail.com>, "avifishman70@gmail.com" <avifishman70@gmail.com>, "tmaimon77@gmail.com" <tmaimon77@gmail.com>, "tali.perry1@gmail.com" <tali.perry1@gmail.com>, "venture@google.com" <venture@google.com>, "yuenn@google.com" <yuenn@google.com>, "benjaminfair@google.com" <benjaminfair@google.com>, "yogeshgaur.83@gmail.com" <yogeshgaur.83@gmail.com>, "konrad.dybcio@somainline.org" <konrad.dybcio@somainline.org>, "alim.akhtar@samsung.com" <alim.akhtar@samsung.com>, "ldewangan@nvidia.com" <ldewangan@nvidia.com>, "thierry.reding@gmail.com" <thierry.reding@gmail.com>, "jonathanh@nvidia.com" <jonathanh@nvidia.com>, "Simek, Michal" <michal.simek@amd.com>, "linux-aspeed@lists.ozlabs.org" <linux-aspeed@lists.ozlabs.org>, "openbmc@lists.ozlabs.org" <openbmc@lists.ozlabs.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, "linux-rpi-kernel@lists.infradead.org" <linux-rpi-kernel@lists.infradead.org>, "linux-amlogic@lists.infradead.org" <linux-amlogic@lists.infradead.org>, "linux-mediatek@lists.infradead.org" <linux-mediatek@lists.infradead.org>, "linux-arm-msm@vger.kernel.org" <linux-arm-msm@vger.kernel.org>, "linux-rockchip@lists.infradead.org" <linux-rockchip@lists.infradead.org>, "linux-samsung-soc@vger.kernel.org" <linux-samsung-soc@vger.kernel.org>, "linux-stm32@st-md-mailman.stormreply.com" <linux-stm32@st-md-mailman.stormreply.com>, "linux-sunxi@lists.linux.dev" <linux-sunxi@lists.linux.dev>, "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>, "netdev@vger.kernel.org" <netdev@vger.kernel.org>, "linux-wpan@vger.kernel.org" <linux-wpan@vger.kernel.org>, "libertas-dev@lists.infradead.org" <libertas-dev@lists.infradead.org>, "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>, "linux-mtd@lists.infradead.org" <linux-mtd@lists.infradead.org>, "lars@metafoo.de" <lars@metafoo.de>, "Michael.Hennerich@analog.com" <Michael.Hennerich@analog.com>, "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>, "michael@walle.cc" <michael@walle.cc>, "palmer@dabbelt.com" <palmer@dabbelt.com>, "linux-riscv@lists.infradead.org" <linux-riscv@lists.infradead.org>, "alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>, "patches@opensource.cirrus.com" <patches@opensource.cirrus.com>, "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>, "amitrkcian2002@gmail.com" <amitrkcian2002@gmail.com>
Subject: RE: [PATCH V5 09/15] spi: Add stacked and parallel memories support in SPI core
Date: Tue, 7 Mar 2023 11:09:41 +0000
Message-ID: <BN7PR12MB2802A2E7A193B8BC0073812BDCB79@BN7PR12MB2802.namprd12.prod.outlook.com>

Hello,

> -----Original Message-----
> From: Jonas Gorski <jonas.gorski@gmail.com>
> Sent: Tuesday, March 7, 2023 1:31 AM
> To: Mahapatra, Amit Kumar <amit.kumar-mahapatra@amd.com>
> Cc: broonie@kernel.org; miquel.raynal@bootlin.com; richard@nod.at;
> vigneshr@ti.com; jic23@kernel.org; tudor.ambarus@microchip.com;
> pratyush@kernel.org; Mehta, Sanju <Sanju.Mehta@amd.com>; chin-
> ting_kuo@aspeedtech.com; clg@kaod.org; kdasu.kdev@gmail.com;
> f.fainelli@gmail.com; rjui@broadcom.com; sbranden@broadcom.com;
> eajames@linux.ibm.com; olteanv@gmail.com; han.xu@nxp.com;
> john.garry@huawei.com; shawnguo@kernel.org; s.hauer@pengutronix.de;
> narmstrong@baylibre.com; khilman@baylibre.com;
> matthias.bgg@gmail.com; haibo.chen@nxp.com; linus.walleij@linaro.org;
> daniel@zonque.org; haojian.zhuang@gmail.com; robert.jarzmik@free.fr;
> agross@kernel.org; bjorn.andersson@linaro.org; heiko@sntech.de;
> krzysztof.kozlowski@linaro.org; andi@etezian.org;
> mcoquelin.stm32@gmail.com; alexandre.torgue@foss.st.com;
> wens@csie.org; jernej.skrabec@gmail.com; samuel@sholland.org;
> masahisa.kojima@linaro.org; jaswinder.singh@linaro.org;
> rostedt@goodmis.org; mingo@redhat.com; l.stelmach@samsung.com;
> davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
> pabeni@redhat.com; alex.aring@gmail.com; stefan@datenfreihafen.org;
> kvalo@kernel.org; james.schulman@cirrus.com; david.rhodes@cirrus.com;
> tanureal@opensource.cirrus.com; rf@opensource.cirrus.com;
> perex@perex.cz; tiwai@suse.com; npiggin@gmail.com;
> christophe.leroy@csgroup.eu; mpe@ellerman.id.au; oss@buserror.net;
> windhl@126.com; yangyingliang@huawei.com;
> william.zhang@broadcom.com; kursad.oney@broadcom.com;
> anand.gore@broadcom.com; rafal@milecki.pl; git (AMD-Xilinx)
> <git@amd.com>; linux-spi@vger.kernel.org; linux-kernel@vger.kernel.org;
> joel@jms.id.au; andrew@aj.id.au; radu_nicolae.pirea@upb.ro;
> nicolas.ferre@microchip.com; alexandre.belloni@bootlin.com;
> claudiu.beznea@microchip.com; bcm-kernel-feedback-list@broadcom.com;
> fancer.lancer@gmail.com; kernel@pengutronix.de; festevam@gmail.com;
> linux-imx@nxp.com; jbrunet@baylibre.com;
> martin.blumenstingl@googlemail.com; avifishman70@gmail.com;
> tmaimon77@gmail.com; tali.perry1@gmail.com; venture@google.com;
> yuenn@google.com; benjaminfair@google.com; yogeshgaur.83@gmail.com;
> konrad.dybcio@somainline.org; alim.akhtar@samsung.com;
> ldewangan@nvidia.com; thierry.reding@gmail.com; jonathanh@nvidia.com;
> Simek, Michal <michal.simek@amd.com>; linux-aspeed@lists.ozlabs.org;
> openbmc@lists.ozlabs.org; linux-arm-kernel@lists.infradead.org; linux-rpi-
> kernel@lists.infradead.org; linux-amlogic@lists.infradead.org; linux-
> mediatek@lists.infradead.org; linux-arm-msm@vger.kernel.org; linux-
> rockchip@lists.infradead.org; linux-samsung-soc@vger.kernel.org; linux-
> stm32@st-md-mailman.stormreply.com; linux-sunxi@lists.linux.dev; linux-
> tegra@vger.kernel.org; netdev@vger.kernel.org; linux-
> wpan@vger.kernel.org; libertas-dev@lists.infradead.org; linux-
> wireless@vger.kernel.org; linux-mtd@lists.infradead.org; lars@metafoo.de;
> Michael.Hennerich@analog.com; linux-iio@vger.kernel.org;
> michael@walle.cc; palmer@dabbelt.com; linux-riscv@lists.infradead.org;
> alsa-devel@alsa-project.org; patches@opensource.cirrus.com; linuxppc-
> dev@lists.ozlabs.org; amitrkcian2002@gmail.com
> Subject: Re: [PATCH V5 09/15] spi: Add stacked and parallel memories
> support in SPI core
> 
> Hi,
> 
> On Mon, 6 Mar 2023 at 18:26, Amit Kumar Mahapatra <amit.kumar-
> mahapatra@amd.com> wrote:
> >
> > For supporting multiple CS the SPI device need to be aware of all the
> > CS values. So, the "chip_select" member in the spi_device structure is
> > now an array that holds all the CS values.
> >
> > spi_device structure now has a "cs_index_mask" member. This acts as an
> > index to the chip_select array. If nth bit of spi->cs_index_mask is
> > set then the driver would assert spi->chip_select[n].
> >
> > In parallel mode all the chip selects are asserted/de-asserted
> > simultaneously and each byte of data is stored in both devices, the
> > even bits in one, the odd bits in the other. The split is
> > automatically handled by the GQSPI controller. The GQSPI controller
> > supports a maximum of two flashes connected in parallel mode. A
> > "multi-cs-cap" flag is added in the spi controntroller data, through
> > ctlr->multi-cs-cap the spi core will make sure that the controller is
> > capable of handling multiple chip selects at once.
> >
> > For supporting multiple CS via GPIO the cs_gpiod member of the
> > spi_device structure is now an array that holds the gpio descriptor
> > for each chipselect.
> >
> > Multi CS support using GPIO is not tested due to unavailability of
> > necessary hardware setup.
> >
> > Signed-off-by: Amit Kumar Mahapatra <amit.kumar-
> mahapatra@amd.com>
> > ---
> >  drivers/spi/spi.c       | 213 +++++++++++++++++++++++++++-------------
> >  include/linux/spi/spi.h |  34 +++++--
> >  2 files changed, 173 insertions(+), 74 deletions(-)
> >
> > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index
> > 5866bf5813a4..8ec7f58fa111 100644
> > --- a/drivers/spi/spi.c
> > +++ b/drivers/spi/spi.c
> > @@ -613,7 +613,8 @@ static int spi_dev_check(struct device *dev, void
> *data)
> >         struct spi_device *new_spi = data;
> >
> >         if (spi->controller == new_spi->controller &&
> > -           spi_get_chipselect(spi, 0) == spi_get_chipselect(new_spi, 0))
> > +           spi_get_chipselect(spi, 0) == spi_get_chipselect(new_spi, 0) &&
> > +           spi_get_chipselect(spi, 1) == spi_get_chipselect(new_spi,
> > + 1))
> >                 return -EBUSY;
> 
> This will only reject new devices if both chip selects are identical, but not if
> they only share one, e.g. CS 1 + 2 vs 1 + 3, or 1 + 2 vs only 2, or if the order is
> different (1 + 2 vs 2 + 1 - haven't read the code too close to know if this is
> allowed/possible).

Agreed,  will add in the next series.

Regards,
Amit
> 
> Regards,
> Jonas