From: Serge Semin <Sergey.Semin@baikalelectronics.ru>
To: Vignesh Raghavendra <vigneshr@ti.com>
Cc: Serge Semin <fancer.lancer@gmail.com>,
Miquel Raynal <miquel.raynal@bootlin.com>,
Richard Weinberger <richard@nod.at>,
Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>,
Maxim Kaurkin <Maxim.Kaurkin@baikalelectronics.ru>,
Pavel Parkhomenko <Pavel.Parkhomenko@baikalelectronics.ru>,
Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>,
Ekaterina Skachko <Ekaterina.Skachko@baikalelectronics.ru>,
Vadim Vlasov <V.Vlasov@baikalelectronics.ru>,
Alexey Kolotnikov <Alexey.Kolotnikov@baikalelectronics.ru>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Arnd Bergmann <arnd@arndb.de>, Lee Jones <lee.jones@linaro.org>,
<linux-mips@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-mtd@lists.infradead.org>
Subject: Re: [PATCH RESEND v2] mtd: physmap: Add Baikal-T1 physically mapped ROMs support
Date: Thu, 28 May 2020 17:38:47 +0300 [thread overview]
Message-ID: <20200528143847.vd7b434xtgiaobv4@mobilestation> (raw)
In-Reply-To: <0a9160b6-f915-2a2b-582f-3e6d657ca7df@ti.com>
On Thu, May 28, 2020 at 04:35:41PM +0530, Vignesh Raghavendra wrote:
>
>
> On 28/05/20 4:12 pm, Serge Semin wrote:
> [...]
> >>> +
> >>> +static map_word __xipram bt1_rom_dummy_read(struct map_info *map,
> >>> + unsigned long ofs)
> >>> +{
> >>> + map_word ret;
> >>> +
> >>> + ret.x[0] = 0xFF;
> >>> +
> >>> + return ret;
> >>> +}
> >> Why define dummy_io for "baikal,bt1-boot-rom"? I don't see any use of
> >> adding a driver that always reads 0xFFs
> > This is supposed to be temporary solution for the baikal,bt1-boot-rom ROM.
> > The Boot ROM mirror might reflect either an embedded firmware or the SPI flash
> > directly mapped into the memory. In former case there is no problem, we can
> > freely read from the Boot ROM region. But in the later case the mirrored region
> > (memory mapped SPI flash) is not always accessible. If normal Boot SPI
> > controller is enabled, then the SPI flash mapping isn't accessible (any attempt
> > will cause a bus-error). In order to fix this we'd need a mutual exclusive lock,
> > which would disable the SPI controller while the mirrored memory mapped SPI flash
> > region needs to be accessed. Such mechanism isn't currently implemented, but it
> > will in be in the framework of my patch created for the SPI subsystem.
> >
> > My idea was to just provide a dummy callback for now and replace it with normal
> > IO-methods with mutual exclusive lock-unlocks when the corresponding SPI driver
> > is accepted.
> >
>
> Yes I understand, but I don't see any advantage for end user by
> providing dummy calls... So please don't add the callbacks until they
> implement proper functionality
Agreed. I'll remove the Baikal-T1 Boot ROM support in the next version.
-Sergey
prev parent reply other threads:[~2020-05-28 14:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-26 22:58 [PATCH RESEND v2] mtd: physmap: Add Baikal-T1 physically mapped ROMs support Serge Semin
2020-05-28 10:06 ` Vignesh Raghavendra
2020-05-28 10:42 ` Serge Semin
2020-05-28 11:05 ` Vignesh Raghavendra
2020-05-28 14:38 ` Serge Semin [this message]
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