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From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>,
	Bin Meng <bmeng.cn@gmail.com>
Cc: Damien Hedde <damien.hedde@greensocs.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	qemu-arm@nongnu.org, Alistair Francis <alistair.francis@wdc.com>,
	qemu-devel@nongnu.org
Subject: Re: [PATCH v2 5/5] hw/char: cadence_uart: Ignore access when unclocked or in reset for uart_{read,write}()
Date: Thu, 2 Sep 2021 08:10:17 +0200	[thread overview]
Message-ID: <e17d9911-2c45-221c-7a05-2dc3c2fa22ce@amsat.org> (raw)
In-Reply-To: <20210901083251.GG6340@toto>

On 9/1/21 10:32 AM, Edgar E. Iglesias wrote:
> On Wed, Sep 01, 2021 at 11:27:24AM +0800, Bin Meng wrote:
>> Read or write to uart registers when unclocked or in reset should be
>> ignored. Add the check there, and as a result of this, the check in
>> uart_write_tx_fifo() is now unnecessary.
> 
> Hi Bin,
> 
> I thought I had replied to this but it must have gotten lost somewhere.
> 
> We've got SW that expects FSBL (Bootlooader) to setup clocks and resets.
> It's quite common that users run that SW on QEMU without FSBL (FSBL typically
> requires the Xilinx tools installed). That's fine, since users can stil use
> -device loader to enable clocks etc.
> 
> To help folks understand what's going, a log (guest-error) message would
> be helpful here. In particular with the serial port since things will go
> very quiet if they get things wrong.

Interesting, I was expecting this error to be reported by
memory_region_access_valid() but indeed it is not in the path.

Alternative is to implement MemoryRegionOps::accepts().


  parent reply	other threads:[~2021-09-02  6:11 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01  3:27 [PATCH v2 0/5] hw/arm: xilinx_zynq: Fix upstream U-Boot boot failure Bin Meng
2021-09-01  3:27 ` [PATCH v2 1/5] hw/misc: zynq_slcr: Correctly compute output clocks in the reset exit phase Bin Meng
2021-09-01  3:27 ` [PATCH v2 2/5] hw/char: cadence_uart: Disable transmit when input clock is disabled Bin Meng
2021-09-01  3:27 ` [PATCH v2 3/5] hw/char: cadence_uart: Move clock/reset check to uart_can_receive() Bin Meng
2021-09-02  2:30   ` Alistair Francis
2021-09-02  6:00   ` Philippe Mathieu-Daudé
2021-09-01  3:27 ` [PATCH v2 4/5] hw/char: cadence_uart: Convert to memop_with_attrs() ops Bin Meng
2021-09-02  2:32   ` Alistair Francis
2021-09-01  3:27 ` [PATCH v2 5/5] hw/char: cadence_uart: Ignore access when unclocked or in reset for uart_{read, write}() Bin Meng
2021-09-01  8:32   ` [PATCH v2 5/5] hw/char: cadence_uart: Ignore access when unclocked or in reset for uart_{read,write}() Edgar E. Iglesias
2021-09-01 10:52     ` Bin Meng
2021-09-02  6:10     ` Philippe Mathieu-Daudé [this message]
2021-09-02  6:09   ` [PATCH v2 5/5] hw/char: cadence_uart: Ignore access when unclocked or in reset for uart_{read, write}() Philippe Mathieu-Daudé
2021-09-02  6:11     ` Philippe Mathieu-Daudé
2021-09-05 14:31       ` Bin Meng

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