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    SubjectRe: [PATCH 23/29] memstick: jmb38x_ms: use DMA for all TPCs with len greater that 8 by default
    --- On Fri, 22/10/10, Maxim Levitsky <maximlevitsky@gmail.com> wrote:

    > From: Maxim Levitsky <maximlevitsky@gmail.com>
    > Subject: [PATCH 23/29] memstick: jmb38x_ms: use DMA for all TPCs with len greater that 8 by default
    > To: "Alex Dubov" <oakad@yahoo.com>
    > Cc: "Andrew Morton" <akpm@linux-foundation.org>, "LKML" <linux-kernel@vger.kernel.org>, "Maxim Levitsky" <maximlevitsky@gmail.com>
    > Received: Friday, 22 October, 2010, 4:53 PM
    > This is to workaround a wierd
    > hardware bug:
    >
    > If PIO write is used, and then after it DMA write is used,
    > DMA
    > engine stops doing writes.
    > That condition even persists after device reset.
    >
    > To be maxumum safe, we do dma to a scratch page
    > and memcpy from/to it.
    >
    > Besides this change should just improve performance.
    >
    > Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
    > ---

    I have not noticed this one before, and for all I know the driver was
    tested at Jmicron.
    Can you explain the issue a bit more?






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