From mboxrd@z Thu Jan  1 00:00:00 1970
From: Vignesh R <vigneshr-l0cyMroinI0@public.gmane.org>
Subject: Re: [RFC PATCH 6/6] spi: Get rid of the spi_flash_read() API
Date: Fri, 16 Feb 2018 15:51:00 +0530
Message-ID: <674d7b22-a3ac-e812-04db-aa0acb1671b0@ti.com>
References: <20180205232120.5851-1-boris.brezillon@bootlin.com>
 <20180205232120.5851-7-boris.brezillon@bootlin.com>
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Cc: Peter Pan <peterpansjtu-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
        Frieder Schrempf <frieder.schrempf-wPoT/lNZgHizQB+pC5nmwQ@public.gmane.org>,
        Yogesh Gaur <yogeshnarayan.gaur-3arQi8VN3Tc@public.gmane.org>,
        =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal-g1n6cQUeyibVItvQsEIGlw@public.gmane.org>,
        Kamal Dasu <kdasu.kdev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Boris Brezillon <boris.brezillon-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org>,
        David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
        Brian Norris <computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
        Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>,
        Marek Vasut <marek.vasut-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
        Richard Weinberger <richard-/L3Ra7n9ekc@public.gmane.org>,
        Cyrille Pitchen <cyrille.pitchen-yU5RGvR974pGWvitb5QawA@public.gmane.org>,
        <linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>, Mark Brown <broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
        <linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
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Hi Boris,

On Tuesday 06 February 2018 04:51 AM, Boris Brezillon wrote:
> From: Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> 
> This API has been replaced by the spi_mem_xx() one, its only user
> (spi-nor) has been converted to spi_mem_xx() and all SPI controller
> drivers that were implementing the ->spi_flash_xxx() hooks are also
> implementing the spi_mem ones. So we can safely get rid of this API.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> ---

>  drivers/spi/spi-ti-qspi.c  | 41 ---------------------------------

> -static bool ti_qspi_spi_flash_can_dma(struct spi_device *spi,
> -				      struct spi_flash_read_message *msg)
> -{
> -	return virt_addr_valid(msg->buf);
> -}
> -


This causes kernel crash because spi_map_buf() now tries to map
vmalloc'd buffers in LPAE backed memory not accessible by 32bit DMA:

ubiattach -p /dev/mtd9
[  114.482439] Unable to handle kernel paging request at virtual address
bf867000
[  114.489689] pgd = 045b2870
[  114.492403] [bf867000] *pgd=ad22c003, *pmd=00000000
[  114.497309] Internal error: Oops: 2a06 [#1] PREEMPT SMP ARM
[  114.502903] Modules linked in: ecdh_generic extcon_usb_gpio
omap_aes_driver omap_sham omap_des des_generic crypto_engine omap_crypto
[  114.514894] CPU: 1 PID: 1862 Comm: ubiattach Not tainted
4.16.0-rc1-next-20180212-00009-gbaa4bd31694e-dirty #16
[  114.525023] Hardware name: Generic DRA74X (Flattened Device Tree)
[  114.531145] PC is at v7_dma_inv_range+0x30/0x48
[  114.535693] LR is at dma_cache_maint_page+0x110/0x124
[  114.540763] pc : [<c0218fdc>]    lr : [<c02149e0>]    p


We need ->can_dma like interface in spi_controller_mem_ops to prevent
such buffers being mapped for certain SoCs. Or SPI NOR framework needs
to use bounce buffers.


-- 
Regards
Vignesh
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